VCS (SVN) Builds not triggering

Using TeamCity version 6.0.2 (build 15857).

I have a project with two build configurations, both set to trigger on changes in an svn repository, but only the first build configuration responds to changes in source control.

The first build config responds to svn changes as expected: changes show up as "pending," and shortly thereafter the build starts. This works fine.

The second project "notices" the changes - ie, they show up as Pending on the Projects screen in TeamCity - but the build never actually starts.

These projects are configured *identically*, except for slight changes in the checkout rules and build runner. They share the same VCS root, and every setting on every screen is identical except for the checkout rules and a parameter for MSBuild:

Checkout rules for Project 1 (working)

-:.
+:Packages
+:libraries
+:www.keil.com/trunk/net.www.keil.com

Checkout rules for Project 2 (not working)

-:.
+:Packages
+:libraries
+:www.keil.com/trunk/asp.www.keil.com



Build runner for Project 1 (working)

Build runner for Project 2 (NOT working)

The only difference is one of the command line parameters.
Project 1 (working)
/p:Configuration=Dev;useWPP_CopyWebApplication=true;OutputPath=c:\build;WebProjectOutputDir=s:\iisshares\http\net.www.keil.com;PipelineDependsOnBuild=false

Project 2 (NOT working)
/p:Configuration=Dev;useWPP_CopyWebApplication=true;OutputPath=c:\build;WebProjectOutputDir=s:\iisshares\http\asp.www.keil.com;PipelineDependsOnBuild=false

I've been through every screen in the both project settings side-by-side, and the only differences I see are the MSBuild parameters and the checkout rules.

HELP.