Problem using Dependency Structure Matrix w/ ant compiled output

I wanted to try the Dependency Structure Matrix new feature out, but when I ran Analyze->Dependency Structure Matrix, it said:

Project class files are out of date.
Do you want o compile a project before continuing DSM analysis?
The refusal to do it might result in incomplete or incorrect data.

If I pick No, it says:

No class files were found.
DSM analysis can't be performed.

I am using Ant tasks to compile and deploy my application. I have set the output path for each module to the same path, i.e. C:\75b\tmp\classes

I can run and debug my applications using this setup, so IDEA is finding the clases, but the Analyze->DSM can't seem to find them.