networkproblemes: sending files

i've a problem with sending files over the network.

it's possible to send files up to 1kb, but if the size is over 1kb, the receiver gets an error.
now i have to splitt the file, which i want to send, into parts with 1kb of size.
is there a possibility to send bigger files?

btw: it works fine local on a computer.

you can split those files and merge at the other end.

EDIT: forgot to mention that what's your buffer size. and all.
sample code would be helpfull.

Paresh