Help with an IF/AND formula please

Hi there, 

My formula is 

=IF(AND(P88>0,O88="T1"),P88*data!$E$16,IF(O88="T1.5",P88*data!$E$17,IF(O88="T2",P88*data!$E$18,)))

where the first bit says if P88 is greater than zero AND 088 = T1, then multiply by P88 on my worksheet called data.

T1 = my pay rate for single time

T1.5 = my pay rate for time and half

T2 = my pay rate for double time.

So if my P88 (hours worked) is greater than zero - multiply it by the T rate.

The problem I have, is if the hours worked is blank, but O88 is set to any of the T's (T1, T1.5, T2), then the cell reports #VALUE!

I want to be able to select the T rate in column O88, and with no hours entered in P88, the result is a blank cell.... because P88>0 should overrule everything.

Any help - much appreciated

Thank you