Try renaming the xml file the datasource is defined in to the following, epus3-ds.xml or oracle-ds.xml. This is how datasources are configured in JBoss running on Linux (note the -ds.xml) i assume it is the same for Windows.
Thanks a lot, that solved the problem. JBoss now binds the datasource as expected. I wonder, if I missed this tiny little naming detail, when I browsed the documentation, or if it just not documented.