is it working fine in QA ?
Did you transported the BADI code till PROD ?
Debug the code in PRD, if I am not wrong in define method of badi you can see the correct assignment (that too in debug mode) whatever value you entered as assignment may be not matching in PRD, where as working fine in DEV and QA.
I am 99% sure, that number assignment is the issue ( as I have faced it earlier).
Thank-You.
Regards,
VB