Is there an error on Schedule 11? Should line 6 read - subtract line 4 from line 5? If income is greater, the higher the deduction for tuition, which doesn't make sense.

On schedule 11 - I noted that if I enter an income of $5,000 for my son he has no deduction for tuition fees.  But if I enter an income of $16,000 he can claim over $2,000 in fees.

Are the calculated fields on Schedule 11 - calculating the appopriate fields from other worksheets?

Thank you.