Unavailable Ant Runner on linux agent

I just did an upgrade from 3.0 to 4.0.2.  When I finished I went about trying to upgrade my linux build agent.  I could see from the log file that it tried to automatically update the agent but it failed after download and shut down the agent.  I manually copied the data from the upgrade directory over the old build agent directory (after making a backup), adjusted the buildAgent.properties file and relaunched the agent.

Now the agent connects but I cannot run any of the builds that used to run on that machine because it says "Incompatible runner: Ant".

The build is set up in the same manner as it used to be before the upgrade where the Build runner is set to Ant and I have Ant home path set to: /usr/share/apache-ant-1.7.0 which is the correct location for this machine.  I am using a machine installed version because we load third party ant tasks with it.

I have not found any documentation on how to set up a runner on the build agent.  I am wondering if the upgrade was not successful.

Here is a line from the agent log that might prove useful:
[2009-03-09 09:59:50,736]   INFO - buildServer.AGENT.registration - Registering on server: [name: linux_bb, ownAddress: 10.181.0.22, ownPort: 9090, buildId: <not running build>, availableRunners: [simpleRunner]]

It looks like the simple runner is the default and I am not sure how to also load the ant runner.  Also I don't know if it is necessary as I am using an Ant installation apart from TeamCity.  How do I get my build running again so it stops complaining about the "Incompatible runner"?