typemockregister error with Auto Deploy

We just purchased TypeMock Enterprise this morning and I'm trying to integrate it into one of our build scripts. I'm using the included NAnt task for license registration, and I get an error like:

You need an enterprise license to use AutoDeploy TypeMock.NET
Error Deploying TypeMock.NET, enterprise license required

My NAnt script is simply:

<target name="ncover">
   <loadtasks assembly="deployTypeMock.NAntBuild.dll" />
   <typemockregister company="-removed-" license="-removed-" autodeploy="true"/>
   <typemockstart link="NCover" profilerlaunchedfirst="true" />
   <!-- Run various tests via NCover/NUnit -->
   <typemockstop/>
</target>

I'm using TypeMock 3.7.1 and it is not installed on the build server. All the various dependencies listed in the documentation on AutoDeploying TypeMock are included as well. I can run the same NAnt script locally (where TypeMock is installed) and the license is registered successfully.

We are using a new 30 day license which was sent when our order was submitted, to use until the permanent one is sent. Could this be the problem? Am I missing something?

Thanks,
Matt Rudder