Hi - I am using DwFunctionManager.AddGlobalFunction<TClass>() to inject a class which contains custom PB functions (static methods).  I am then using my function in an expression when using IDataStore.Evaluate().  I am having an issue when my string column is null.  If the string column has a value the fxn works.  For example...

My static function in my class:

        public static string AddPrefix(string value)
        {
            string retVal = string.Empty;
            if (!string.IsNullOrEmpty(value)) retVal = "Mr. " + value;
            return retVal;
        }

Using fxn in expression:

IDataStore.Evaluate("AddPrefix(colName)",0);

When the column is null it does not appear to find the fxn maybe due to a different datatype expected in the param? The error message states:

System.NotSupportedException
  HResult=0x80131515
  Message=Method: addprefix
  Source=SnapObjects.Data
  StackTrace:
   at SnapObjects.Expressions.EvaluatePolicyProvider.TryInvokeMethod(String name, Object args, ParserOptions`1 options, Object& result)
...

Any suggestions on how I can get this global fxn to work if my string column is null as well as when it has data without having to check for null in my expression.  I am OK with creating a 2nd fxn with a different param to return empty string if the column is null (if necessary).  I am asking because I have clients which create their own expressions using pre-defined global PowerBuilder fxns that my company has created.  I am evaluating creating a C# library or Web API with these new tools and cannot expect clients to change their existing expressions.

Thanks,