Using svn with cron?

I've been struggling all morning with what should be a very simple problem.

I would like to commit and update a svn repository daily using cron. I've
encapsulated my svn calls into a perl script, which runs the following

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#!/usr/bin/perl
print "To run svn commit\n";
$thetime=time;
system "cd ~/docs; /usr/bin/svn commit --message '$thetime' \n";
system "cd ~/docs; /usr/bin/svn info \n";
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The whole thing is >> to a file in my /tmp directory for monitoring. 
The script works fine if I run it manually. 
In the monitoring file, I see the correct output from svn info after the 
cronjob, but it looks like the "svn commit" never runs. I don't see any output 
from it and the revision never changes.
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To run svn commit
Path: .
URL: svn://xxremoved
Repository Root: svn://xxremoved
Repository UUID: xxremoved
Revision: 487
Node Kind: directory
Schedule: normal
Last Changed Rev: 487
Last Changed Date: 2011-03-06 04:42:01 -0800 (Sun, 06 Mar 2011)
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(I do have some file changes there to force a commit)
Does anyone know why svn info would work while svn commit would not?
Thanks, 
- Jonathan