Access 2016 Public Sub error - User Defined Type Not

Question

Upgraded from Access 2013 to 2016 which uses a custom ribbon. In the Main Module, I declare a Public Sub as follows which bombs out right from the get go saying User -Defined Type Not defined. Any thoughts? 'Callback for Form OnButtonPress Public Sub FrmButtonPress(Control As IRibbonControl) On Error GoTo FrmButtonPress_Err DoCmd.OpenForm Control.Tag FrmButtonPress_Exit: Exit Sub FrmButtonPress_Err: MsgBox "Error:" & Err.Number & vbCrLf & Err.description, vbCritical, "Warning" Resume FrmButtonPress_Exit End Sub