Form 8829 and Schedule A

I'm finding the questions about home office mortgage interest and property taxes very confusing in Turbo Tax. First of all, when filling out the home office business section, you don't know at the point whether you will qualify to itemize deductions or not, since the personal deduction section is later.  You have to jump around.  Having said that, when I answer the questions about "excess real estate taxes", the form doesn't seem to be filling out correctly. Somehow, my property tax was doubled on the Schedule A which clearly isn't correct. What could be causing that? Please make this section more clear!  I itemized last year, and will take the standard deduction this year.