I have a CASE list on Sheet 1 as:

CASE BRANCH ID#

Sheet 2 has a BRANCH list like:

BRANCH ID#-MISSING

I want the cell Sheet2!B2 to be lookingup through the complete list in
Sheet1 and return an "X" if ANY of the CASES in the corresponding branch in
Sheet2!A2 has no ID.

What sort of formula should I try?

Thanx in advance.