Thanks Chip and Rick for your help! You got me thinking. I
accomplished what I was after with this:

Select Case IsDate(Cells(r, "K").Value)
Case Is < Date
MsgBox "You have not entered a valid date. Please re-
enter."
Cells(r, "K").Select
Case Else

Select Case Weekday(Cells(r, "K").Value)
Case 1, 7

MsgBox "You have entered a weekend date." _
& vbLf & "Please enter the date for Friday, or the
date for Monday!"
Cells(r, "K").Select

End Select
End Select

Again, my thanks!
Ken