Streaming Server issue....!!

i have created a mobile application for sony ericsson w300 which plays a 3gp file throughDARWIN STREAMING SERVER.

My application is a success. But the problem is that, I am able to play the default 3gp file given by the server. But, when i try to play a 3gp file created by me, then my application doesn't play the file.

Can anyone please help me out with a solution. Are there any specification that should be kept in mind while creating the 3gp file.