need help with formula for time

I'm trying to calculate the number of hours worked when it crosses over to a new day. For instance, 15:00 to 2 a.m. the next day. When I use the formula +b2-a2+if(a2>b2,1) the result is .54. Can anyone tell me what I can do to resolve this and come up with the correct value of 12 hours? I've also tried using 24 in place of the 1 and it gives me the same result.

Please help!

I got the help I needed from the Cpearson.com site.

Thanks for your help!