MouseLeftButtonDown is not getting fired

I have a WPF user control that is dervied from UserControl class. MouseLeftButtonDown is not getting fired at all for the contol. I added event handler and also tried as follows. I guess it is handled somewhere else, how to debug and find where is it getting hanlded.. Any help is appreciated!

protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e开发者_StackOverflow)
{
    base.OnMouseLeftButtonDown(e); 
} 

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Did you have the Background of the UserControl set to something? If not, try setting it to "Background=Transparent" and see if that works. If it doesn't work, can you post the XAML for your UserControl, as well as the XAML for its usage?