rsync using proxy server

[sergey kapustin]

Hello all!
I'm trying to syncronize 2 directories on 2 servers (A and B) using
3rd server (C) as proxy server.

what i did is:
 - installed http proxy (tinyproxy) on C and configured it to run on
port 873 - default port for rsync protocol.
 - set the variable RSYNC_PROXY to C-ip:873 using command
    export RSYNC_PROXY=C-ip:873
 - run the rsync command without ssh support.

as a result the directories are syncronized, but the proxy is not used.
What can be the problem, please?