Take the code from {
http:#25760172} but replace the name of the combo with Combo12. It changes only one line:
stCriteria = "DepartmentName = '" & Combo12 & "'"
Basically, this is the crux of the matter; you will recognize {
http:#25754264} and {
http:#25754286}, variations of the "short answer" to your question.
(°v°)