drag drop is not working on premiere extension

Hello all,

I'm a new user in Flex. And now, I'm trying to create premiere plugin.

-the issue is that I use drag and drop event on desktop app,works nice, when I debug it for Premiere Extension, access the extension on premiere and the event not working succesfully.

The error is  Error #1034: Type Coercion failed: cannot convert mx.events::DragEvent@7fff8465a19 to mx.events.DragEvent.

Both same events and already worked in desktop app. Is that a bug or what I'm missing ?

Thanks in advance