Multiplying formula results

I'm creating a cost tracker but am struggling with some multiplication formulas. I've used the IF statement to return an hourly rate i.e. if role is X then hourly rate is £250, this is working as expected. However when I try to multiply an hours column by the rate returned in the IF formula I get an #INVALIDOPERATION error.

So my question is whether it whether it is possible to use the result of a formula in a new multiplication formula. Total hours is keyed in and when hourly rate is keyed in the * formula works but when hourly is returned from an IF statement it doesn't. Am I attempting something that is not possible?