How to check textbox field length dynamically

[access]

Hi All,



I'm new to MS Access forms. I have a combobox with 3 fields A, B, C. and a textbox. When the option B is selected the length of the characters in textbox should not exceed 3. I'm trying to write VBA code for this as below

Private Sub TEXTBOX_KeyPress(KeyAscii As Integer)
If [TEXTBOX].length && [COMBOBOX] = "B" Then
MsgBox "Error"
End Sub

But the "length" field is not available in TEXTBOX, Could any one of you please let me know on how to resolve this.

Thanks you.

[RuralGuy]

If Len(Me.TextBox.Text) > 3 AND Me.ComboBox = "B" Then