Can't send files in xmpp chat

I use eM Client to log as my xmpp chat client in my work, but I have a problem:
I receive files through chat, but I can’t send files to the same person. We use a intranet openfire server, and although we use proxy for internet connections, the connection with the openfire server is direct. If you need more info I’ll be glad to send.
I’m using eMClient 4.0.13961.0 as default email em xmpp chat client.

can you send any files using some other client?
Could you please send us your XMPP logs so we can analyze it? Go to: Tools - Settings - Logging, check XMPP, try to simulate the issue and send us the logs using the same window. Thank you.