Call up the User record for the Attorney through File Maintenance Manager, Tools, Mange Users.  Access the Rates Tab and make sure the attorney has a Rate Code set up for the amount you want.  If he does, make sure the Effective Date is on or before the oldest date of the WIP you are trying to change. If he does not, add a new Rate Code for the correct dollar amount and use an Effective Date that is on or before the oldest date of the WIP.  Once you have done that, go back into Bill Prep and try to change the Rate Code on the WIP (remember, when you change the rate in Bill Prep through Global Edit, you are choosing a Rate Code and not a dollar amount).