controlling the focus of a textbox

[EDUCATED MONKEY]

Hello all my set up office 2007 win xp pro IE 8
Can anyone suggest away to toggle between two textboxes by the click of a command button at present I have a clear command button the clears the textbox should the wrong code be scanned and set the focus of the textbox

Private Sub BtnClear_Click()
TextBoxIsbn.Value = ""
TextBoxIsbn.SetFocus
End Sub

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The aim is to take the input from a barcode reader; the difficulty is that barcodes are of different lengths in my case 13 or 10 digits, at the moment I use the code below to detect 13 digits so I was hoping to set up a similar situation with a 10 digit textbox
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Private Sub TextBoxIsbn_Change()
Dim MyData As Variant
If Len(TextBoxIsbn.Value) = 13 Then
MyData = TextBoxIsbn.Value
Module11.SaveData (MyData)    ‘ all this does is find the next available row in a particular worksheet
End If
End Sub