Index: Ringtoets/Revetment/src/Ringtoets.Revetment.Service/WaveConditionsCalculationServiceBase.cs
===================================================================
diff -u -r87b3dec8abf9077375a10deb16d508d9cc2711e4 -re674bb3e0b3e4f2e66080348b8e6acfa48137bb1
--- Ringtoets/Revetment/src/Ringtoets.Revetment.Service/WaveConditionsCalculationServiceBase.cs	(.../WaveConditionsCalculationServiceBase.cs)	(revision 87b3dec8abf9077375a10deb16d508d9cc2711e4)
+++ Ringtoets/Revetment/src/Ringtoets.Revetment.Service/WaveConditionsCalculationServiceBase.cs	(.../WaveConditionsCalculationServiceBase.cs)	(revision e674bb3e0b3e4f2e66080348b8e6acfa48137bb1)
@@ -36,6 +36,7 @@
 using Ringtoets.HydraRing.IO;
 using Ringtoets.Revetment.Data;
 using Ringtoets.Revetment.Service.Properties;
+using RingtoetsCommonFormsResources = Ringtoets.Common.Forms.Properties.Resources;
 using RingtoetsCommonServiceResources = Ringtoets.Common.Service.Properties.Resources;
 
 namespace Ringtoets.Revetment.Service
@@ -290,7 +291,20 @@
                 }
             }
 
+            if (double.IsNaN(input.Orientation))
+            {
+                return string.Format(RingtoetsCommonServiceResources.Validation_ValidateInput_No_value_entered_for_0_,
+                                     GenerateParameterNameWithoutUnits(RingtoetsCommonFormsResources.Orientation_DisplayName));
+            }
+
             return null;
         }
+
+        private static string GenerateParameterNameWithoutUnits(string parameterDescription)
+        {
+            string[] splitString = parameterDescription.Split('[');
+            return splitString.Length != 0 ? splitString[0].ToLower().Trim() : string.Empty;
+        }
+
     }
 }
\ No newline at end of file