Index: Riskeer/Common/src/Riskeer.Common.Forms/Properties/Resources.Designer.cs
===================================================================
diff -u -rc1a92b999dcc6a79240c5d16710942cde7ad6669 -r48a0e44c21b690f38b0e5eea605f4d83a9519d58
--- Riskeer/Common/src/Riskeer.Common.Forms/Properties/Resources.Designer.cs	(.../Resources.Designer.cs)	(revision c1a92b999dcc6a79240c5d16710942cde7ad6669)
+++ Riskeer/Common/src/Riskeer.Common.Forms/Properties/Resources.Designer.cs	(.../Resources.Designer.cs)	(revision 48a0e44c21b690f38b0e5eea605f4d83a9519d58)
@@ -182,6 +182,15 @@
         }
         
         /// <summary>
+        ///   Looks up a localized string similar to De duidingsklassen per vak voor dit toetsspoor..
+        /// </summary>
+        public static string AssemblyGroups_Description {
+            get {
+                return ResourceManager.GetString("AssemblyGroups_Description", resourceCulture);
+            }
+        }
+        
+        /// <summary>
         ///   Looks up a localized string similar to Duidingsklassen.
         /// </summary>
         public static string AssemblyGroups_DisplayName {
Index: Riskeer/Common/src/Riskeer.Common.Forms/Properties/Resources.resx
===================================================================
diff -u -rc1a92b999dcc6a79240c5d16710942cde7ad6669 -r48a0e44c21b690f38b0e5eea605f4d83a9519d58
--- Riskeer/Common/src/Riskeer.Common.Forms/Properties/Resources.resx	(.../Resources.resx)	(revision c1a92b999dcc6a79240c5d16710942cde7ad6669)
+++ Riskeer/Common/src/Riskeer.Common.Forms/Properties/Resources.resx	(.../Resources.resx)	(revision 48a0e44c21b690f38b0e5eea605f4d83a9519d58)
@@ -1630,6 +1630,9 @@
     <data name="AssemblyGroups_DisplayName" xml:space="preserve">
     <value>Duidingsklassen</value>
   </data>
+    <data name="AssemblyGroups_Description" xml:space="preserve">
+    <value>De duidingsklassen per vak voor dit toetsspoor.</value>
+  </data>
     <data name="AssemblyGroup_Name_DisplayName" xml:space="preserve">
     <value>Naam</value>
   </data>
Index: Riskeer/Integration/src/Riskeer.Integration.Forms/PropertyClasses/AssemblyGroupsProperties.cs
===================================================================
diff -u -rc1a92b999dcc6a79240c5d16710942cde7ad6669 -r48a0e44c21b690f38b0e5eea605f4d83a9519d58
--- Riskeer/Integration/src/Riskeer.Integration.Forms/PropertyClasses/AssemblyGroupsProperties.cs	(.../AssemblyGroupsProperties.cs)	(revision c1a92b999dcc6a79240c5d16710942cde7ad6669)
+++ Riskeer/Integration/src/Riskeer.Integration.Forms/PropertyClasses/AssemblyGroupsProperties.cs	(.../AssemblyGroupsProperties.cs)	(revision 48a0e44c21b690f38b0e5eea605f4d83a9519d58)
@@ -58,7 +58,7 @@
         [PropertyOrder(failureMechanismSectionAssemblyCategoryPropertyIndex)]
         [ResourcesCategory(typeof(RiskeerCommonFormsResources), nameof(RiskeerCommonFormsResources.Categories_General))]
         [ResourcesDisplayName(typeof(RiskeerCommonFormsResources), nameof(RiskeerCommonFormsResources.AssemblyGroups_DisplayName))]
-        [ResourcesDescription(typeof(RiskeerCommonFormsResources), nameof(RiskeerCommonFormsResources.AssemblyGroups_DisplayName))]
+        [ResourcesDescription(typeof(RiskeerCommonFormsResources), nameof(RiskeerCommonFormsResources.AssemblyGroups_Description))]
         [TypeConverter(typeof(ExpandableArrayConverter))]
         public AssemblyGroupProperties[] FailureMechanismAssemblyGroups
         {
@@ -70,10 +70,13 @@
 
         private AssemblyGroupProperties[] GetFailureMechanismAssemblyGroups()
         {
-            var assessmentSection = Data as AssessmentSection;
+            if (Data is AssessmentSection assessmentSection)
+            {
+                return AssemblyToolGroupBoundariesFactory.CreateFailureMechanismSectionAssemblyGroupBoundaries(
+                    assessmentSection.FailureMechanismContribution.SignalingNorm, assessmentSection.FailureMechanismContribution.LowerLimitNorm).Select(category => new AssemblyGroupProperties(category)).ToArray();
+            }
 
-            return AssemblyToolGroupBoundariesFactory.CreateFailureMechanismSectionAssemblyGroupBoundaries(
-                assessmentSection.FailureMechanismContribution.SignalingNorm, assessmentSection.FailureMechanismContribution.LowerLimitNorm).Select(category => new AssemblyGroupProperties(category)).ToArray();
+            return Array.Empty<AssemblyGroupProperties>();
         }
     }
 }
\ No newline at end of file
Index: Riskeer/Integration/test/Riskeer.Integration.Forms.Test/PropertyClasses/AssemblyGroupsPropertiesTest.cs
===================================================================
diff -u -rc1a92b999dcc6a79240c5d16710942cde7ad6669 -r48a0e44c21b690f38b0e5eea605f4d83a9519d58
--- Riskeer/Integration/test/Riskeer.Integration.Forms.Test/PropertyClasses/AssemblyGroupsPropertiesTest.cs	(.../AssemblyGroupsPropertiesTest.cs)	(revision c1a92b999dcc6a79240c5d16710942cde7ad6669)
+++ Riskeer/Integration/test/Riskeer.Integration.Forms.Test/PropertyClasses/AssemblyGroupsPropertiesTest.cs	(.../AssemblyGroupsPropertiesTest.cs)	(revision 48a0e44c21b690f38b0e5eea605f4d83a9519d58)
@@ -77,7 +77,7 @@
             PropertiesTestHelper.AssertRequiredPropertyDescriptorProperties(failureMechanismSectionCategoriesProperty,
                                                                             generalCategoryName,
                                                                             "Duidingsklassen",
-                                                                            "Duidingsklassen",
+                                                                            "De duidingsklassen per vak voor dit toetsspoor.",
                                                                             true);
         }
     }