Room and Board expense raises tax due

I am a bit confused by Room and Board for college expenses.  We got to the screen in TT where we can enter in amounts that were not included in the 1098-T "allowed" amount.  It says "Elementary and Secondary School Expenses".  When I entered in the amount of money which had been paid by me for R&B (which was a line item on my son's college bill), my taxes due really increased.  They jumped.  Why would I get penalized for paying for R&B (an expense)?   If I just omit that number my taxes go down about 2K.  I'm so confused.  We did pay for R&B with a 529 withdrawal which is on a 1099-Q and I am the recipient.