Schema Error

Dear Experts,

I have written PCR for Mid-Month joining. This PCR is inserted in Schema INN1 copied to ZNN1, below INEPF Function as shown below:

The problem is with parameter IF. If I enter IF, I get below message:

If I save this, and run the payroll, I get below error in Payroll:

I want to add IF

Please tell me where I am making mistake in Schema?

Thanks and Regards,

Bhagyashree