svn sync error svn_path_is_empty

Hi,

I am trying to create Write-through proxying using docs @ link:
http://svnbook.red-bean.com/en/1.7/svn.serverconfig.httpd.
html#svn.serverconfig.httpd.extra.writethruproxy
I took dump of master repo and imported it on slave repo.
I configured pre_revprop_change hook and changed UUID and sync URL in slave
repo.

When I am trying to do svn sync I am getting below error.

svn01-mel:/var/lib/svn# svnsync sync --non-interactive --source-username
upload --source-password xxxxxxxx --sync-username svnsync
--sync-password xxxxxxxx https://svn01-bom.domain.com/
svn-proxy-sync/websites
svnsync:
/tmp/buildd/subversion-1.6.12dfsg/subversion/libsvn_subr/path.c:414:
svn_path_is_empty: Assertion `is_canonical(path, strlen(path))' failed.
Aborted
Following are the properties of slave repo.

svn01-mel:/var/lib/svn# svn pl --revprop -v -r 0 --username svnsync
--password xxxxxxxx http://svn01-bom.domain.com/svn-proxy-sync/websites/
Unversioned properties on revision 0:
  svn:sync-from-uuid
    8d27d823-bff0-0310-a57f-b904fce7d886
  svn:sync-lock
    svn01-mel:ad538f1a-609a-452f-9fdb-9bc63db55a38
  svn:sync-last-merged-rev
    79426
  svn:date
    2005-02-23T03:17:40.923186Z
  svn:sync-from-url
    https://svn.domain.com/svn/websites/

Any pointers.

-- 
Regards
Pravin