16 bit MS-DOS Subsystem Error

Dear All...
i know that i could not find any answer here... but trying to ask again...

im facing a problem.. im trying to install a softwear on windows 2000, this softwear runs on windows 98 very well.. when i try to run this softwear in win 2k i recieve an error msg,,,

"Invalid program file name, please check your pif file. Choose 'Close' to terminate the application."

I know that this is Dos version problem. but can anyone tell me the way so dat i could fix that problem...
it will be very kind of you all...
waiting for some gud response.

Thanks.