rsync error: protocol incompatibility (code 2) at compat.c(62)

Hi, I am not very familiar with rsync, so I would really appreciate
somebody's help on this one.
I have two machines running the exact same version of rsync:

rsync version 2.5.7 protocol version 26

and I keep getting the above error. Here is the commmand that I run:

rsync -e ssh -avvvz <user>@<remotehost>:/home/<user>
/home/<user>/dest/

and the response that I get:

protocol version mismatch - is your shell clean?
(see the rsync man page for an explanation)
rsync error: protocol incompatibility (code 2) at compat.c(62)
_exit_cleanup(code=2, file=compat.c, line=62): about to call exit(2)

Both rsyncs are running as daemons and have an identical rsyncd.conf
file.

Could anyone point me in the right direction here, please?
Thanks in advance.

I got it. My problem was with the "interactive" vs. "non-interactive"
shell. On one of the machines, there was a command run on login, which
apparently confused rsync. Works great now!