No Transport provider Available

I have written a transport provider that works with Outlook 2000. I tessted it on the Windows NT m/c and it worked fine. But later as my intended client was Windows 2000, i checked it on Windows 2000 and it gave me a Non delivery report as soon as Itried to send a mail. The Outlook 2000 was configured in Corporate network mode. It gives a NDR saying that No transport provider is available. Do I need to modify anything in my code ? or do I need to modify any settings that differ in windows 2000frm win NT ?
It doesnt even call the SubmitMessage method in my transport provider.
Please help !
This is URGENT