Cursor control on a data entry form

Hi
I have a data entry form, I want the cursor just after the default value, I add On Got Focus event but  does not work..
Private Sub DM_Number_GotFocus()
Me![DMNumber].SelStart = 4
Me![DMNumber].SelLength = 2
End Sub
Total data length of the field is 6. therefore allowed to add/enter 3 digits
I am expecting the cursor position 4th field of the text box, DMNumber is the text box name.
Even if it possible to position the cursor after the default value of the text box by property setting of the text box that would be great.
Also, how to make it allowed only capital letter in default, is there any setting in the table design make it possible or property setting of the textbox make it default as capital letter.

Thanks