IF statement unable to process negatives

Hello,

I have a problem with an IF statement, i have a "sheet value" and a "Revenue" value, the sheet value may be higher or lower than the revenue value, thus giving either a + or - value, i'm trying to get a return if the difference between the sheet and revenue is less than 10%, i have tried my own formula but it won't work with negative values, i have attached a worksheet with an example

thanks reg