Index: Riskeer/Common/src/Riskeer.Common.Forms/Views/FailureMechanismResultView.cs
===================================================================
diff -u -r2ba01760465d876044dc832ed6e023385d616086 -rc370b3c3bbc7c598f347a3f48a2dd0567dc18581
--- Riskeer/Common/src/Riskeer.Common.Forms/Views/FailureMechanismResultView.cs	(.../FailureMechanismResultView.cs)	(revision 2ba01760465d876044dc832ed6e023385d616086)
+++ Riskeer/Common/src/Riskeer.Common.Forms/Views/FailureMechanismResultView.cs	(.../FailureMechanismResultView.cs)	(revision c370b3c3bbc7c598f347a3f48a2dd0567dc18581)
@@ -140,7 +140,6 @@
             DataGridViewControl.CellFormatting += HandleCellStyling;
 
             UpdateInternalViewData();
-            UpdateFailureMechanismAssemblyControls();
         }
 
         /// <summary>
@@ -183,11 +182,12 @@
             UpdateDataGridViewDataSource();
             UpdateAssemblyData();
             UpdateProbabilityResultTypeCombobox();
+            UpdateFailureMechanismAssemblyControls();
         }
 
         private void UpdateProbabilityResultTypeCombobox()
         {
-            probabilityResultTypeComboBox.Enabled = FailureMechanism.Sections.Any();
+            probabilityResultTypeComboBox.Enabled = HasSections();
         }
 
         private void RefreshDataGrid()
@@ -217,11 +217,16 @@
 
         private void UpdateFailureMechanismAssemblyControls()
         {
-            failureMechanismAssemblyProbabilityTextBox.Enabled = IsManualAssembly() && FailureMechanism.Sections.Any();
-            failureMechanismAssemblyProbabilityTextBox.ReadOnly = !IsManualAssembly();
+            failureMechanismAssemblyProbabilityTextBox.Enabled = IsManualAssembly() && HasSections();
+            failureMechanismAssemblyProbabilityTextBox.ReadOnly = !IsManualAssembly() && !HasSections();
             failureMechanismAssemblyProbabilityTextBox.Refresh();
         }
 
+        private bool HasSections()
+        {
+            return FailureMechanism.Sections.Any();
+        }
+
         private void UpdateAssemblyData()
         {
             ClearErrorMessage();
@@ -374,8 +379,13 @@
             failureMechanismAssemblyProbabilityTextBox.Text = ProbabilityFormattingHelper.FormatWithDiscreteNumbers(probability);
 
             FailureMechanismAssemblyResult assemblyResult = FailureMechanism.AssemblyResult;
-            if (assemblyResult.IsManualProbability())
+            bool hasManualProbability = assemblyResult.IsManualProbability();
+            if (hasManualProbability && !HasSections())
             {
+                SetErrorMessage("Om een oordeel te kunnen invoeren moet voor het faalmechanisme een vakindeling zijn geimporteerd.");
+            }
+            else if (hasManualProbability)
+            {
                 SetErrorMessage(FailureMechanismAssemblyResultValidationHelper.GetValidationError(assemblyResult));
             }
         }
Index: Riskeer/Common/test/Riskeer.Common.Forms.Test/Views/FailureMechanismResultViewTest.cs
===================================================================
diff -u -r2ba01760465d876044dc832ed6e023385d616086 -rc370b3c3bbc7c598f347a3f48a2dd0567dc18581
--- Riskeer/Common/test/Riskeer.Common.Forms.Test/Views/FailureMechanismResultViewTest.cs	(.../FailureMechanismResultViewTest.cs)	(revision 2ba01760465d876044dc832ed6e023385d616086)
+++ Riskeer/Common/test/Riskeer.Common.Forms.Test/Views/FailureMechanismResultViewTest.cs	(.../FailureMechanismResultViewTest.cs)	(revision c370b3c3bbc7c598f347a3f48a2dd0567dc18581)
@@ -828,6 +828,11 @@
                     ManualFailureMechanismAssemblyProbability = 0.1
                 }
             };
+            FailureMechanismSection section = FailureMechanismSectionTestFactory.CreateFailureMechanismSection("Section 1");
+            FailureMechanismTestHelper.SetSections(failureMechanism, new[]
+            {
+                section
+            });
 
             using (TestFailureMechanismResultView view = ShowFailureMechanismResultView(failureMechanism.SectionResults, failureMechanism, assessmentSection, (fm, ass) => throw new AssemblyException(exceptionMessage)))
             {
@@ -850,7 +855,32 @@
 
             mocks.VerifyAll();
         }
+        
+        [Test]
+        public void FailureMechanismResultViewWithoutSectionsAndProbabilityTypeManual_ReturnsCorrectError()
+        {
+            // Setup
+            const string expectedErrorMessage = "Om een oordeel te kunnen invoeren moet voor het faalmechanisme een vakindeling zijn geimporteerd.";
+            var failureMechanism = new TestFailureMechanism
+            {
+                AssemblyResult =
+                {
+                    ProbabilityResultType = FailureMechanismAssemblyProbabilityResultType.Manual
+                }
+            };
 
+            // Call
+            using (TestFailureMechanismResultView view = ShowFailureMechanismResultView(failureMechanism.SectionResults, failureMechanism))
+            {
+                ErrorProvider errorProvider = GetErrorProvider(view);
+                TextBox failureMechanismAssemblyProbabilityTextBox = GetFailureMechanismAssemblyProbabilityTextBox();
+                string errorMessage = errorProvider.GetError(failureMechanismAssemblyProbabilityTextBox);
+                
+                // Assert
+                Assert.AreEqual(expectedErrorMessage, errorMessage);
+            }
+        }
+
         [Test]
         [TestCase(true)]
         [TestCase(false)]
@@ -903,7 +933,7 @@
         }
 
         [Test]
-        public void FailureMechanismResultView_WithoutSections_FailureMechanismAssemblyProbabilityTextBoxDisabled()
+        public void FailureMechanismResultView_WithoutSections_FailureMechanismAssemblyProbabilityTextBoxCorrectState()
         {
             // Setup 
             var failureMechanism = new TestFailureMechanism();
@@ -915,14 +945,21 @@
                 TextBox textBox = GetFailureMechanismAssemblyProbabilityTextBox();
                 CollectionAssert.IsEmpty(failureMechanism.Sections);
                 Assert.IsFalse(textBox.Enabled);
+                Assert.IsTrue(textBox.ReadOnly);
             }
         }
 
         [Test]
-        public void FailureMechanismResultView_WithSections_FailureMechanismAssemblyProbabilityTextBoxEnabled()
+        public void FailureMechanismResultView_WithSections_FailureMechanismAssemblyProbabilityTextBoxCorrectState()
         {
             // Setup 
-            var failureMechanism = new TestFailureMechanism();
+            var failureMechanism = new TestFailureMechanism
+            {
+                AssemblyResult =
+                {
+                    ProbabilityResultType = FailureMechanismAssemblyProbabilityResultType.Manual
+                }
+            };
 
             using (ShowFailureMechanismResultView(failureMechanism.SectionResults, failureMechanism))
             {
@@ -941,6 +978,7 @@
 
                 // Assert
                 Assert.IsTrue(textBox.Enabled);
+                Assert.IsFalse(textBox.ReadOnly);
             }
         }
 
@@ -1020,6 +1058,11 @@
                     ManualFailureMechanismAssemblyProbability = manualProbability
                 }
             };
+            FailureMechanismSection section = FailureMechanismSectionTestFactory.CreateFailureMechanismSection("Section 1");
+            FailureMechanismTestHelper.SetSections(failureMechanism, new[]
+            {
+                section
+            });
             failureMechanism.AssemblyResult.Attach(observer);
 
             using (TestFailureMechanismResultView view = ShowFailureMechanismResultView(failureMechanism.SectionResults, failureMechanism))
@@ -1066,6 +1109,11 @@
                     ManualFailureMechanismAssemblyProbability = manualProbability
                 }
             };
+            FailureMechanismSection section = FailureMechanismSectionTestFactory.CreateFailureMechanismSection("Section 1");
+            FailureMechanismTestHelper.SetSections(failureMechanism, new[]
+            {
+                section
+            });
             failureMechanism.AssemblyResult.Attach(observer);
 
             using (TestFailureMechanismResultView view = ShowFailureMechanismResultView(failureMechanism.SectionResults, failureMechanism))