Mbox + Reaktor Session Plug-in, confused.. Options

[guerillamedia]

I recently just purchased Reaktor Session (Native Instruments Software) and I want to run it on my Mac G5 as a plugin with Pro Tools LE 6.4 w/MBox. I was able to get it working as a standalone with the sounds coming out of the built in output of the G5. I wanted the output to go through the mbox but it wasn't listed in the dropdown in the audio + midi settings within Reaktor. I figure if it channeled through pro tools as a plugin, it would automatically go through the mbox. Unfortunately it doesn't.....any thoughts?