I want to set up a formula to do the following. The formula is placed in
column A:
Look in column B for a specific text string. If that value is in column B,
copy it to column A
If the value is not found in B, leave A alone (either blank, or the existing
value of A)

I've tried the followign:
=IF(B1="XX",B1,A1)

however, if I do this and the value is NOT found in column B, the resulting
value is 0.

Any suggestions?