Create Event Procedure Via Code

I'm trying to add a worksheet event via code. It works OK when I run it on its own but I get a run-time error 9 subscript out of range error when I try to run it from another procedure.

Please find attached my 2 bits of code. Any help greatly appreciated.

This is the bit that works OK on its own but not when called from my other procedure


Sub Code_To_Write_Code()

'This writes code to the new sheet

Dim StartLine As Long
Dim SheetToAddCodeTo
SheetToAddCodeTo = ActiveSheet.CodeName

With ActiveWorkbook.VBProject.VBComponents(SheetToAddCodeTo).CodeModule
StartLine = .CreateEventProc("Calculate", "Worksheet") + 1 ..............