Not detecting VCS changes for a tag as I expected

I set up two identical build configurations to check how team city would do at detecting revisions, triggering a build from the revisions, and then reporting revisions.  The only difference between the two build configurations is that one is for HEAD and the second is for a Tag.
Here are my steps

1. I added the java project to CVS and tagged it RA1
2.  I created the HEAD build config, and the RA1 build config
3.  I made change to the source file in the project, committed it, and tagged it RA1
4.  HEAD build config detected the change and built and reported the change correctly.
5.  RA1 did not detect the change.
6.  When I clicked Run for the RA1 build config, it built, but did not report any changes.


So does this mean that I should avoid using the Checkout  by Tag option to get the full benefit of the CI Server for detecting  changes to the VCS?


I can still do builds based on Tags like this,  but it so far does not look like I can trigger off changes or see the  changes made between builds.

Using 6.5 EAP of TeamCity

The log from teamcity-vcs is attached.