I have 7 rental properties. Why, when I add some of my legitimate expenses for the last one or two of the buildings, my "taxes due" number increased by about $2,000?

I have 7 rental properties and when I added $7109 for HOA expenses for the last building, my taxes due increased by about $1500. Is there a problem with the software? The amount of taxes due increased when I added the amount above as well as when I added my mortgage interest for the building. I am money ahead by not listing about $8500 in expenses.