Validation formula in PI sheet

Hi,

Using function module in PI sheet, i'm getting the result of the function module i'm passing into a Variable RD1. I written the validation formula as follows.

In the above screen,SD is my input variable in the PI sheet screen

But, i'm not getting the validation check while doing the transaction.

Please help me to get the validation in the CO60 screen.

Thanks in advance.

Naren