About Messaging with driver and app

Hi~ there all...

I've greate thanks to NTDev group ... and Happy new year you all..

and..

I am develop Network IM driver based on Windows2000, It started "passthru" DDK example....
That works very well... BUT I cann't communicate with app... I was built on device name and make symbolic link...

and in APP, use DeviceIOControl and CreateFile .. this is very common method for DeviceDriver communication... But That was useless...
Cann't get Driver handle value... Plz help me...

Thanks to you all

bye..