I'm having trouble with dates entered via a userform. When
I enter a date in the format dd/mm/yyyy everything is ok.
I then go and work out the work days between the 2 dates
entered. When I next enter the form it shows my date in
the format mm/dd/yyyy and if I don't notice and re-enter
the date I work out the wrong work days.

What do I need to do to get around this problem?

Data entered from a userform doesn't seem to take any
notice of cell format definitions. The cell is defined as
date of type 14/03/2001.

The user enters a start and end date then clicks a button
which has the associated code:

If Not IsDate(Me.TB_A1_SDt.Text) Then
MsgBox ("Must be a valid Date!")
Me.TB_A1_SDt.Text = ""
Me.TB_A1_SDt.SetFocus
Else
If Not IsDate(Me.TB_A1_ED.Text) Then
MsgBox ("Must be a valid Date!")
Me.TB_A1_ED.Text = ""
Me.TB_A1_ED.SetFocus
Else
Sheets("AutumnHT1").Cells(2, 1).Formula = CVDate
(UserForm1.TB_A1_SDt.Text)
Sheets("AutumnHT1").Cells(1, 4).Formula = CVDate
(UserForm1.TB_A1_ED.Text)
Unload UserForm1
Load UserForm2
UserForm2.Show
Exit Sub
End If
End If

End Sub

I needed to use the CVDATE function to ensure that it was
copied from the userform to the cell as a valid date
otherwise it was text.