setting focus back to a textbox

Question

I need to check if a text box is empty/null or blank before my user moves onto the next field on the user form. here is the code that checks if the textbox is empty/null/blank. My issue is that it does not return the focus to the textbox, but moves onto the next field in the user form.

Private Sub txtTDYLocation_lostfocus()
Dim Pcase As String
    'converts text to proper case
    
    If Trim(txtTDYLocation.Value & "") = "" Then
        MsgBox "Please enter TDY location", vbOKOnly
        txtTDYLocation.SetFocus
    Else
        Pcase = Me.txtTDYLocation
        Pcase = StrConv(Pcase, vbProperCase)
        Me.txtTDYLocation.Text = Pcase
        Me.txtTDYLocation = StrConv(Me.txtTDYLocation, 3)
   End If
End Sub

Answer 1

For this to work you should use the event txtTDYLocation_BeforeUpdate and cancel the change if value is Null in the textbox. Once Cancel is set to True the focus will not be able to leave the textbox.

Private Sub txtTDYLocation_BeforeUpdate(Cancel As Integer)
    If Trim(txtTDYLocation & "") = "" Then
        MsgBox "Please enter TDY location", vbOKOnly
        Cancel = True
    End If
End Sub

And in txtTDYLocation_AfterUpdate() you can change the value.

Private Sub txtTDYLocation_AfterUpdate()
    Dim Pcase As String
    'converts text to proper case
    If Trim(txtTDYLocation.Value & "") <> "" Then
        Pcase = Me.txtTDYLocation
        Pcase = StrConv(Pcase, vbProperCase)
        Me.txtTDYLocation.Value = Pcase
        Me.txtTDYLocation = StrConv(Me.txtTDYLocation, 3)
   End If
End Sub