uncosted material transactions error out with failure:Final_Acct( 0 ): -6502 Error in CSTPSCWF.START

 Dear Friends,

Every month few material transactions error out with the message: failure:Final_Acct( 0 ): -6502 Error in CSTPSCWF.START_STD_WFORA-06502: PL/SQL: numeric or value error.

I have tried searching in the metalink for this error but did not get much information on what exactly is the root cause of this issue.

Based on the error message 06502: PL/SQL: numeric or value error, i suspect the issue is because of data because one this error occurs usually 

1. when we are try to assign a value larger than a variable can handle.

2. when we try to assign non-numeric value to a number variable