diff --git a/PROMS/VEPROMS.CSLA.Library/Config/ROFSTLookup.cs b/PROMS/VEPROMS.CSLA.Library/Config/ROFSTLookup.cs
index 2a018517..11505ce1 100644
--- a/PROMS/VEPROMS.CSLA.Library/Config/ROFSTLookup.cs
+++ b/PROMS/VEPROMS.CSLA.Library/Config/ROFSTLookup.cs
@@ -172,7 +172,8 @@ namespace VEPROMS.CSLA.Library
 							return child.value;
 				}
 			}
-			return null;
+			if (ROID.StartsWith("FFFF")) return string.Format("Invalid Unit RO '{0}'", ROID);
+			return string.Format("Invalid RO '{0}'",ROID);
 		}
 		public rochild GetRoChild(string ROID)
 		{