problems with svnmerge

I just committed Ariel's csd changes to the 99 branch, and when I
attempted to merge I first got a failure and now the branch is not
showing up in the available branches. Any ideas? The branch was
listed on a 'svnmerge.py merge' command *before* the failure.

jdhunter@...687...:mpl> svnmerge.py merge
/home/jdhunter/dev/bin/svnmerge.py:71: DeprecationWarning: The popen2
module is deprecated. Use the subprocess module.
  import sys, os, getopt, re, types, tempfile, time, popen2, locale
svnmerge: multiple sources found. Explicit source argument
(-S/--source) required.
The merge sources available are:
  /branches/v0_99_maint
  /branches/mathtex

jdhunter@...687...:mpl> svnmerge.py merge -Sv0_99_maint
/home/jdhunter/dev/bin/svnmerge.py:71: DeprecationWarning: The popen2
module is deprecated. Use the subprocess module.
  import sys, os, getopt, re, types, tempfile, time, popen2, locale
property 'svnmerge-integrated' set on '.'

svnmerge: command execution failed (exit code: 1)
svn --non-interactive propdel "svnmerge-blocked" "."
svn: Attempting to delete nonexistent property 'svnmerge-blocked'

jdhunter@...687...:mpl> svnmerge.py merge -Sv0_99_maint
/home/jdhunter/dev/bin/svnmerge.py:71: DeprecationWarning: The popen2
module is deprecated. Use the subprocess module.
  import sys, os, getopt, re, types, tempfile, time, popen2, locale
svnmerge: "v0_99_maint" is neither a valid URL, nor an unambiguous
substring of a repository path, nor a working directory

jdhunter@...687...:mpl> svnmerge.py merge
/home/jdhunter/dev/bin/svnmerge.py:71: DeprecationWarning: The popen2
module is deprecated. Use the subprocess module.
  import sys, os, getopt, re, types, tempfile, time, popen2, locale
svnmerge: multiple sources found. Explicit source argument
(-S/--source) required.
The merge sources available are:
  /branches/v0_91_maint
  /branches/mathtex
  /branches/v0_98_5_maint