file adapter and large file

hi experts, i have a problem:

i have configured sender file adapter to send 4mb file from FTP server, so when i upload file to FTP, file adapter don't upload it, file just stay in folder.

I have tried to upload small file, is about 16kb, so it works fine, without any errors

.

I checked communication channel log in RWB, there are not any errors, all leds are green.

So i don't know how to upload 4mb file, also i checked all rights and permissions for file and user, they all have admin rights - "777".

Can anybody give me some suggestion or solution?

Thanks all for reply.