If I do this:

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
    Dim rCell As Range
    With Range(tCell)
        If .Value = Empty Then
            Application.EnableEvents = False
            .Select
            MsgBox "Please enter the number of pages required."
            Application.EnableEvents = True
        End If
    End With
    Select Case Target.Address
        Case "A$14","$G$14", "$L$14"
            If Target = "P" Then Target = "" Else Target = "P"
    End Select
End Sub
I get this error- Haha, and now it works, of course. Wow. There is still one issue, however. I don't know how difficult the fix would be, but by clicking any of the cells listed in the second part of the code (A14, G14, or L14) the first part of the code (which requires a page number to be entered before any other cell gets data entered) gets bypassed and the checkbox cell gets changed. The Message Box does appear, but after clicking OK, the checkbox cell that was clicked changes.

Is there something we can change to solve this?