Can't assign value

[Mike Collard]

I have form with several text boxes that are populated by
a procedure when the user makes a selection from a combo
box.

I want to create a Cancel button to undo any unsaved
changes so I have copied the following code from the
Access Help file but get 'error 2448. Can't assign value
to this object.'

Sub btnUndo_Click()

Dim ctlC As Control
' For each control.
For Each ctlC In Me.Controls
If ctlC.ControlType = acTextBox Then
' Restore Old Value.
ctlC.Value = ctlC.OldValue
End If
Next ctlC

End Sub

Any ideas?