Index: DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/DamMacroStabilityCommon/MStabXmlDoc.cs
===================================================================
diff -u -r1007 -r1026
--- DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/DamMacroStabilityCommon/MStabXmlDoc.cs	(.../MStabXmlDoc.cs)	(revision 1007)
+++ DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/DamMacroStabilityCommon/MStabXmlDoc.cs	(.../MStabXmlDoc.cs)	(revision 1026)
@@ -180,7 +180,7 @@
             }
 
             // Make sure riverlevel is correct with respect to surfaceline
-            double riverLevelLow = double.NaN;
+            double? riverLevelLow = null;
             if (failureMechanismParametersMStab.MStabParameters.GridPosition == MStabGridPosition.Left && scenario.RiverLevelLow.HasValue)
             {
                 riverLevelLow = scenario.RiverLevelLow.Value;