Programmatically update label in mainwindow from user control viewmodel

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WPF

C#7.1

I have a label in my mainwindow that I am trying to update from a user control viewmodel. But no matter what I have tried it does not update.

These are the fields in the mainwindow.

<Grid Height="30" Width="190" HorizontalAlignment="Center" Margin="900, 145, 20, 0" VerticalAlignment="Top">
        <StackPanel Orientation="Horizontal" VerticalAlignment="Top" HorizontalAlignment="Right" Height="25" Margin="0, 0, 0, 0" Width="190">
        <Label x:Name="lblFederal" HorizontalAlignment="Right" Content="{Binding Amts.FederalTotal}" Width="90" Height="25" FontSize="10pt" />
        <Label x:Name="lblState" HorizontalAlignment="Right" Content="{Binding Amts.StateTotal}" Width="90" Height="25" Margin="15, 0, 0, 0" FontSize="10pt" />
    </StackPanel>
</Grid>

What I have tried:

Here is my code from my user control viewmodel.

   MainWindow _mainWindow;
   MainWindowVM _mainWindowVM;

_mainWindow.lblFederal.Content = "20";
_mainWindowVM.Amts.FederalTotal = "20";
_mainWindowVM.updateAmounts(20, 20);