Test if moving off a cell without choosing a value

[Tom Melosi]

Is it possible to test whether a value has been entered in a cell before they
move from that cell?

The user will pick a code from a list in column B. I have a
Worksheet_Change event that populates a data creates a validation list in
column D based on the code the user picks. The event then selects the cell
the data validation was created for (same row, but in column D).

Is there a way to make sure the user enters or picks a value fromt the data
validation list?

Thanks