Adding time values for no sequence cells with an IF function

I need help please adding times values as follows:
If cell A1 contains (AAA or BBB) to add three hours to cell B1. If cell A1 contains (CCC or DDD to add two hours instead to cell B1
Cell B1 contains time values, example 25/05/2011 20:40:00
I tried the below formula but it reflected an error.

=IF((OR(A1="AAA",A1="BBB"),(B1+TIME(3,0,0),"")),IF((OR(A1="CCC",A1="DDD"),(B1+TIME(2,0,0""))