Native drag not work on my PC

Hello. I want to implement dragging an image from a system to air app. I'm using NativeDragManager and NativeDragEvent. NativeDragManager.isSupported is true for me. But events never fired. I asked my colleagues to run my code on their pc - it works. I downloaded Scrappy example from here http://www.adobe.com/devnet/air/flash/quickstart/articles/scrappy_copy_paste.html. Installed example works fine, but if I compile it by myself - it not works - events never fire. And dragging above target shows me "not allowed" icon.