State tax filing

I don't understand how the program can be correct. I'm entitled to a deduction of $25k (married couple with 5 beneficiaries) but when I input this amount, in the system, my MD tax liability increases by about $1000 vs. when I input a contribution amount of, say, $12,500.  I spoke to a rep (not a tax expert) who was unable to explain this and generally was not helpful.  I thought about upgrading for "expert tax advice" but the cost would be $100 (50 for federal and 50 for state) and I suspect the outcome would be equally unsatisfactory.  At this point, I'm thinking I may have to do my taxes with a professional tax preparer/accountant to ensure I'm getting it right.