SVN Merge fails with SVN_IS_VALID_REVNUM

Having trouble merging a branch with the trunk.

The branch I am trying to merge is a copy of another branch, which branched from the original trunk several revisions ago. The google search for the variable retur开发者_JAVA百科ns very little. Is what I am trying to do even feasible?

[jeff@jeff prod2.3]# svn merge -r 4723:6643 http://svn.hello.com/svn/repos/trunk/

svn: In file 'subversion/libsvn_client/merge.c' line 2711: assertion failed (SVN_IS_VALID_REVNUM( revision_primary_url_deleted))

UPDATE: Solved the issue see answer below.

Was able to solve the issue when I dug deeper into the SVN versions. Turns out the I had already done a previous merge at R5231 and that had something to do with the error. When I merged at that revision it worked fine. Luckily I had written down where that merge occurred because otherwise I would have never been able to find out without digging into commit messages.

svn merge -r 5231:6643 http://svn.hello.com/svn/repos/trunk/