Did you connect an isr component to the interrupt output?
Can you please post your complete project, so that we all can have a look at all of your settings. To do so, use
Creator->File->Create Workspace Bundle (minimal)
and attach the resulting file.
Please check the attached file. The example code has both Tx and Rx interrupt(External). The example should give an output stream "ABCDEF..." on your terminal. This may help you to make necessary changes to your settings.