Index: Riskeer/Common/src/Riskeer.Common.Service/Structures/StructuresCalculationServiceBase.cs
===================================================================
diff -u -r9d221c80e414846f872fdfcef0683b6bf053b404 -r2036ec39c88e223d438212abcb4a753078e21236
--- Riskeer/Common/src/Riskeer.Common.Service/Structures/StructuresCalculationServiceBase.cs	(.../StructuresCalculationServiceBase.cs)	(revision 9d221c80e414846f872fdfcef0683b6bf053b404)
+++ Riskeer/Common/src/Riskeer.Common.Service/Structures/StructuresCalculationServiceBase.cs	(.../StructuresCalculationServiceBase.cs)	(revision 2036ec39c88e223d438212abcb4a753078e21236)
@@ -324,8 +324,7 @@
             }
 
             string connectionValidationProblem = HydraulicBoundaryDataConnectionValidator.Validate(
-                assessmentSection.HydraulicBoundaryData,
-                input.HydraulicBoundaryLocation);
+                assessmentSection.HydraulicBoundaryData, input.HydraulicBoundaryLocation);
 
             if (!string.IsNullOrEmpty(connectionValidationProblem))
             {
Index: Riskeer/Revetment/src/Riskeer.Revetment.Service/WaveConditionsCalculationServiceBase.cs
===================================================================
diff -u -ref0e33f806405ecf81ec625bfc5c0d5b0f0729d8 -r2036ec39c88e223d438212abcb4a753078e21236
--- Riskeer/Revetment/src/Riskeer.Revetment.Service/WaveConditionsCalculationServiceBase.cs	(.../WaveConditionsCalculationServiceBase.cs)	(revision ef0e33f806405ecf81ec625bfc5c0d5b0f0729d8)
+++ Riskeer/Revetment/src/Riskeer.Revetment.Service/WaveConditionsCalculationServiceBase.cs	(.../WaveConditionsCalculationServiceBase.cs)	(revision 2036ec39c88e223d438212abcb4a753078e21236)
@@ -206,22 +206,26 @@
                                               WaveConditionsInput input,
                                               RoundedDouble assessmentLevel)
         {
-            var validationResults = new List<string>();
-
-            string connectionValidationProblem = HydraulicBoundaryDataConnectionValidator.Validate(hydraulicBoundaryData);
-            if (!string.IsNullOrEmpty(connectionValidationProblem))
+            if (input.HydraulicBoundaryLocation == null)
             {
-                validationResults.Add(connectionValidationProblem);
+                return new[]
+                {
+                    RiskeerCommonServiceResources.CalculationService_ValidateInput_No_hydraulic_boundary_location_selected
+                };
             }
 
-            if (validationResults.Any())
+            string connectionValidationProblem = HydraulicBoundaryDataConnectionValidator.Validate(
+                hydraulicBoundaryData, input.HydraulicBoundaryLocation);
+
+            if (!string.IsNullOrEmpty(connectionValidationProblem))
             {
-                return validationResults.ToArray();
+                return new[]
+                {
+                    connectionValidationProblem
+                };
             }
 
-            validationResults.AddRange(ValidateWaveConditionsInput(input, assessmentLevel));
-
-            return validationResults.ToArray();
+            return ValidateWaveConditionsInput(input, assessmentLevel).ToArray();
         }
 
         private void NotifyProgress(RoundedDouble waterLevel, int currentStepNumber, int totalStepsNumber)
@@ -378,12 +382,8 @@
         {
             var messages = new List<string>();
 
-            if (input.HydraulicBoundaryLocation == null)
+            if (double.IsNaN(assessmentLevel))
             {
-                messages.Add(RiskeerCommonServiceResources.CalculationService_ValidateInput_No_hydraulic_boundary_location_selected);
-            }
-            else if (double.IsNaN(assessmentLevel))
-            {
                 messages.Add(Resources.WaveConditionsCalculationService_ValidateInput_No_AssessmentLevel_calculated);
             }
             else