If i’ve tried every answer to put for the nonrefundable credit amt, and it won’t take any answer i put, even if i put exactly what it tells me it should be, what do i do?

i’ve put 1, it’ll say it must be 0. i’ll put 0, then it’ll say it needs to be blank. i’ll leave it blank, it must have an answer. i type the word blank, it won’t even let me type letters, only numbers