Is he getting a refund of all of the taxes that he paid to Massachusetts? If so, he wouldn't be eligible for the credit.
If he's not getting a refund of everything he paid to Massachusetts, the next thing to check is the type of return he's filing for Massachusetts. Is it a resident of non-resident return? If it's a resident return, he wouldn't get a credit in Pennsylvania. The credit is only for taxes paid to a nonresident state.
If he's not getting a refund of all of his taxes and he's filing a nonresident MA return, did you add the MA information on the PA return for the other state tax credit? The credit is calculated on a per-state basis. The amount for CA and MA won't be added together. They'll each have their own Schedule G/L.
