Please help : Strange 'file has vanished' behaviour with rsync on windows.

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Actually I would want to use ssh and do copy between two remote servers from my machine.
But the following did not work:
 rsync -e ssh -av user at mypc1:/myshare1/dir1 user at mypc2:/myshare2/dir2

I was not able to successfully rsync with both, source and destination, as remote locations. 
I would appreciate if you can tell me whether there is a limitation in rsync or am I doing something wrong?

regards,