how to change a combobox based on selection, number field to 0 on a main access form

Hey there any help will be appreciated Thanks I got a combobox field = name(txtCombo) And a numberField = (txtNumber)

Im getting a error something wrong with my code any help will be highly appreciated.Thanks

Private Sub txtCombo_Click()
If Me.txtCombo.Value = "Meter" Then
Me.txtNumber.Value = 0
End If
End Sub
error imn my code:

Run time error: '2448' You cant assign a value to a object, due to this code I cant continue my calcuation!!!

If I select the Meter value it must change the txtNumber to 0