=IF(AND(SUMIF(Form!I1:I100,"C",Form!N1:N100)-form2!G14<1.1,SUMIF(Form!I1:I100,"C",Form!N1:N100)-form2!G14-1.1),"ok","check")

I have a formula like this. I doubt check every cell and these related two
forms. They have valid data there. Could someone give me a hint where I might
find the problem? Thanks.