Deductions & credits

According to the IRS, the Internet and your own answer to "Re: Can you explain..." above, the maximum long term capital gains tax rate should be between 15 and 20%.  However, in my return, my capital gains of 18,000 are being taxed at the maximum Trust account rate of 37 percent- giving me an overall rate of 28% before NIIT.  This should be mathematically impossible- so I'm thinking that there is a bug in the program which is causing long term capital gains income to be taxed as regular income.  PLEASE HELP!!!!