For an income or expense category to show up under Business you have to assign it a Schedule C tax line number. Go into Edit Category and assign it one. If you need to see a schedule C, here's the blank form….http://www.irs.gov/pub/irs-pdf/f1040sc.pdf
You can either assign the tax line number to an existing category or you might want to set up a new category for it to keep the existing one under personal if you have the same expense for both personal and business.