How about propagating back the error to the caller?

Code:
Private Sub Command1_Click()
    On Error GoTo Command1_Click_Err
    Test
Exit Sub

Command1_Click_Err:
    MsgBox Err.Description
End Sub

Private Sub Test()
    On Error GoTo ErrorHandler
    Err.Raise 100, , "test"
    Exit Sub
ErrorHandler:
    MsgBox Err.Description
    Err.Raise Err.Number, Err.Source, Err.Description
End Sub