I have a formula that reads =IF(I135-J135=0,"OK","ERROR")

I can see that the figures in cells I135 & J135 are identical so I should
get a return of "OK" but I get "ERROR" instead. Could be something to do
with rounding ? if so how do I amend the formula to cope with this. (Note, I
have the same formula on two other worksheets in the same workbook, and they
both work fine !)

any suggestions, greatly appreciated