Problem with NetConnection in Adobe AIR(Flex) using Flash Media Server.

Hi

I am creating a small chat application using Flash Media server. I have already created all my user interface components in Flex(Adobe AIR).In this application rather than sending text messages user can also  send  file to another user in his friend list.

problem what i am facing is, when i am sending file through FMS most of time it send successfully but for some files while sending  application loss netconnection.

so i would like to know, rather than closing application what are other condition when FMS loses network connection?

Any help would be appreciated .

Thanks.