I don't use Vlookup much and it's not working for me. I know it's user error
so can you tell me what I did wrong?

I have two worksheets in my file. In the first one, I have a list of
addresses with a full unabbreviated US state name in column T, row 2. Column
U is blank because I want to put the two-digit state code in there (starting
with U2).

In the second worksheet I have the full state name in Column A and the
two-digit code for it in Column B (rows 1-50).

Here's my formula starting in U2:

=VLOOKUP(T2,StateCodes!$A$1:$B$50,2,FALSE)

What is wrong?