AutoCAD Inventor :: InputListBox Gives An Unhandled Exception Error

I'm working on some iLogic code but it gives me an error

The strange thing is that the error apperase when i use the code as an External Rule.

When i copy the code to a Rule (local rule) the error does not appear.

In both rules the code works correct, but i like to use it as an External Rule, without the error.

I have made a User Parameter: "Keuze" that hase a Multivalue.
 
Dim oPartDoc as PartDocument = ThisDoc.DocumentDim userParams As UserParameters = oPartDoc.ComponentDefinition.Parameters.UserParametersTry Keuze_Params = oPartDoc.ComponentDefinition.Parameters("Keuze")Catch Dim newParam As UserParameter = userParams.AddByValue("Keuze", "", UnitsTypeEnum.kTextUnits)End TryMultiValue.List("Keuze") = GoExcel.CellValues("C: empiLogic.xlsx", "Sheet1", "A2", "A6")Keuze= InputListBox("Huidige keuze: "& iProperties.Value("Project", "Description"), MultiValue.List("Keuze"), Keuze, Title := "Keuzelijst:", ListName := "Type keuze")If Keuze = Nothing Then Exit Sub LineNumber=GoExcel.FindRow("C: empiLogic.xlsx", "Sheet1", "Naam", "=", Keuze)iProperties.Value("Project", "Description") = GoExcel.CurrentRowValue("Code")