I have an existing project that I want to build in the IntelliJ Community Edition 11.1.4 running on Ubuntu 12.04.1 LTS
In the Ant Build window I added the project\'s
IDEA just prints Ant's output. Try switching the output from the tree view to the plain text view using the corresponding button on the left of the messages panel:

If the output contains errors, you should be able to see them there.
Also it's much faster and easier to use IDEA provided incremental compilation (Build | Make).