Trigger Alt from KeyPress

Question

I want to detect Alt, or Alt + some key, from within Form1_KeyPress. This is my code:

    private void Form1_KeyPress(object sender, KeyPressEventArgs e)
    {

        if (Control.ModifierKeys == Keys.Alt)
        {
            MessageBox.Show("Alt");
        }
        if (Control.ModifierKeys == Keys.Control)
        {
            MessageBox.Show("Control");
        }
    }

When I hit Ctrl + A for example, the second if triggers. However when I hit Alt + A for example, nothing happens. Why is that? is there some other way to trigger Alt from Form1_KeyPress? I don't want to trigger it from KeyDown in this instance.