Cannot Select the Audio Output and stops on first beat of count-in when I press play

I have been using Ireal pro for a few years on my iphone, Ipad and Macbook with no problem ....
I decided to install on my mac Pro with OS 10.9.5 installed ( This mac is my pro music app and I use a Digidesign 003 interface for audio output)
I installed Ireal pro 6.01 and when I press play, I see the count in spinning and then it just stops without any sound ... so I went inside my mac's system preference and selected built-in outputs, but same thing.
Finally I went into the Audio output on the left bottom corner of Ireal Pro but no output is available ....
every other program on my mac works fine ( Logic, Protools, Youtube from safari, System sounds etc... )
What am I doing wrong ? why can't I select a output ?

Thanks for your help

Update :
after trying many different options, I found a way of making it work :
If I turn off my audio interface and start Ireal Pro, it will show the built-in outputs .... I then start my audio interface and select it back in the OS System Preferences , then I can select my interface in Ireal Pro ...
Not very convenient but at least it works ... :-)
I'm still wondering if that is a bug or if I'm missing something ?

Thanks

We haven't had reports of such issues since OS X 10.8
Make sure that the Digidesign drivers are updated to the latest version.

They are the latest version and not 10.8 but 10.9.5
Again I only have this problem with Ireal Pro ... any other app using audio driver works as expected ...
thanks for your reply though

Hello, I have tested with 4 different interfaces (unfortunately not Digidesign—my Mbox 2 is not supported). The interfaces would just show up in the Audio Output menu in iReal Pro when plugged in and turned on.
Have you tried restarting your Mac?
Also you could trash your drivers (uninstall) and re-install them (and presumably it will require a restart after installation).

Yes I have tried everything But no luck ...
It's not a big deal though , all I have to do is turn my interface off, start IrealPro, power up my interface and wait for it to show up in the audio menu .
just takes a couple more minutes but works great ....
Thanks for the great app :-)
P.S. If you need a beta tester for digi interface, let me know ;-)