Capital gains tax in two states

We are MA residents who sold a family home in MD. Having a difficult time trying to figure out the credit for capital gains tax paid in MD. The MA Form 1 worksheet and instructions are geared for income tax credits. We paid over 12,000 to MD, part of which was non- resident tax. We also paid over 8,000 to MA. The MA return by our MD- based accountant listed a MA state credit for only about $900. This doesn't seem right. Any ideas how we can check accuracy? Or why the credit was so low? Thanks.