Time formula problems!

I am trying to convert the number of days which is an integer into hours (HH,MM) then add this value onto another value which is also in HH,MM format to give a total time of the two times added together.

This formula gives me the number of days as an integer (1 = 24hours, 2 = 48 etc.)

CurrentDate - {KRISS_SLA_BE.ul_date}

This is the formula i am trying to use to convert the integer into hours and then add it onto a different time formula

IF {@CURRENT DATE} = 1 THEN ({@TIME LEFT} + 24)

ELSE

IF {@CURRENT DATE} = 2 THEN ({@TIME LEFT} + 48)

It keeps saying a number is required!

Any help is greatly appreciated.

Thanks,

Kriss