Truncating a part number in a BOM table using relations

Hi

I we have just changed over to Creo2

I have a part number 12345-56-78-001_old i want the BOM table cell to read 12345-56-78-001, i used to have some notes on how to do this but i have mis laid them.

Our company uses &asm.mbr.name to report the part number 12345-56-78-001_old in the BOM table

I have tried several methods of writing a relation in the table to 'crop' the drawing number but without sucess, here are some of the relations i have tried

if asm_mbr_name == "12387-10-60-001_OLD"
new_name = "12387-10-60-001"
else
new_name = asm_mbr_name
endif
if asm_mbr_name == "12387-10-60-001_OLD"
asm_mbr_name = "12387-10-60-001"
endif
if asm_mbr_name == "12387-10-60-001_OLD"
asm_mbr_name = extract(asm_mbr_name, 1, 15)
endif

None of the above have worked for me! anyone got a solution?

thanks

Richard