Index: dam engine/trunk/src/Deltares.DamEngine.Interface/FillDamFromXmlInput.cs
===================================================================
diff -u -r730 -r734
--- dam engine/trunk/src/Deltares.DamEngine.Interface/FillDamFromXmlInput.cs	(.../FillDamFromXmlInput.cs)	(revision 730)
+++ dam engine/trunk/src/Deltares.DamEngine.Interface/FillDamFromXmlInput.cs	(.../FillDamFromXmlInput.cs)	(revision 734)
@@ -100,7 +100,7 @@
         {
             if (input.StabilityParameters != null)
             {
-                var curSpec = damProjectData.DamProjectCalculationSpecification?.CurrentSpecification;
+                var curSpec = damProjectData.DamProjectCalculationSpecification.CurrentSpecification;
                 if (curSpec != null)
                 {
                     curSpec.FailureMechanismeParamatersMStab = new FailureMechanismeParamatersMStab();
Index: dam engine/trunk/src/Deltares.DamEngine.Interface/FillXmlInputFromDam.cs
===================================================================
diff -u -r730 -r734
--- dam engine/trunk/src/Deltares.DamEngine.Interface/FillXmlInputFromDam.cs	(.../FillXmlInputFromDam.cs)	(revision 730)
+++ dam engine/trunk/src/Deltares.DamEngine.Interface/FillXmlInputFromDam.cs	(.../FillXmlInputFromDam.cs)	(revision 734)
@@ -104,10 +104,10 @@
 
         private static void TransferStabilityParameters(DamProjectData damProjectData, Input input)
         {
-            if (damProjectData.DamProjectCalculationSpecification?.CurrentSpecification != null)
+            if (damProjectData.DamProjectCalculationSpecification != null && damProjectData.DamProjectCalculationSpecification.CurrentSpecification != null)
             {
-                var curSpec = damProjectData.DamProjectCalculationSpecification?.CurrentSpecification;
-                if (curSpec.FailureMechanismeParamatersMStab?.MStabParameters != null)
+                var curSpec = damProjectData.DamProjectCalculationSpecification.CurrentSpecification;
+                if (curSpec.FailureMechanismeParamatersMStab != null && curSpec.FailureMechanismeParamatersMStab.MStabParameters != null)
                 {
                     input.StabilityParameters = new StabilityParameters();
                     input.StabilityParameters.SearchMethod = ConversionHelper.ConvertToInputSearchMethod(curSpec.FailureMechanismeParamatersMStab.MStabParameters.SearchMethod);
Index: dam engine/trunk/src/Deltares.DamEngine.Interface/ConversionHelper.cs
===================================================================
diff -u -r730 -r734
--- dam engine/trunk/src/Deltares.DamEngine.Interface/ConversionHelper.cs	(.../ConversionHelper.cs)	(revision 730)
+++ dam engine/trunk/src/Deltares.DamEngine.Interface/ConversionHelper.cs	(.../ConversionHelper.cs)	(revision 734)
@@ -952,6 +952,11 @@
             return translationTable[tangentLineType];
         }
 
+        /// <summary>
+        /// Converts to tangent lines definition.
+        /// </summary>
+        /// <param name="tangentLineType">Type of the tangent line.</param>
+        /// <returns></returns>
         public static TangentLinesDefinition ConvertToTangentLinesDefinition(int tangentLineType)
         {
             var translationTable = new Dictionary<int, TangentLinesDefinition>()