Maven2 scm:update goal not working

We have several modules that build using the maven2 scm:update goal, which works from the command line and in CruiseControl. However, after setting up the same modules in TeamCity, I am receiving the following error:

:
: Executing: svn --non-interactive update
: Working directory: D:\TeamCity\buildAgent\work\2007.4.JCT\4X\storage
: Provider message:
: The svn command failed.
: Command output:
: svn: PROPFIND request failed on '/svn/enrollment/branches/2007.4.JCT/4X/storage'
: svn: PROPFIND of '/svn/enrollment/branches/2007.4.JCT/4X/storage': authorization failed (http://bfvcs1)

Why am I failing to be authorized through TeamCity, when I can run both mvn scm:update and svn --non-interactive update from the command line using the same user credentials? This was working last week for some of the modules, but others have never worked.

Thanks for your help.