Hi Superman,
I don't believe you could do both with Data Validation (create the drop-down list AND check to see if a date is in column A of that row). For that you could use a worksheet_change even macro like the one below:
Any time you change a value in column B to Complete it will check to see if a valid date exists in column A for that row. If not, the user will get a warning message and the last change will be undone. If yes, the user won't see any message (it will allow them to change the status).
Hope that helps!
Bookmarks