diff --git a/PROMS/VEPROMS.CSLA.Library/Config/SectionConfig.cs b/PROMS/VEPROMS.CSLA.Library/Config/SectionConfig.cs
index 2e77d024..888df42b 100644
--- a/PROMS/VEPROMS.CSLA.Library/Config/SectionConfig.cs
+++ b/PROMS/VEPROMS.CSLA.Library/Config/SectionConfig.cs
@@ -795,7 +795,10 @@ namespace VEPROMS.CSLA.Library
 			}
 			set
 			{
-				_Xp["MasterSlave", "Applicability"] = value.FlagList;
+				if (value != null)
+					_Xp["MasterSlave", "Applicability"] = value.FlagList;
+				else
+					_Xp["MasterSlave", "Applicability"] = null; 
 				OnPropertyChanged("MasterSlave_Applicability");
 			}
 		}