I think I see what's going on. Sorry, I was using MIDI tracks when I tested this and misunderstood the issue.
In Band-in-a-Box, there's a dedicated Reverb control on the mixer, which affects all tracks, audio or MIDI. For MIDI tracks, it sends a MIDI CC to whatever synth you're using, to turn up the synth's built-in reverb.
For audio tracks, it sends the audio of that track to a reverb effect that's built into BIAB.
In RealBand, reverb is handled the same way with MIDI tracks. MIDI tracks all have a dedicated Reverb knob, which sends a MIDI CC to your synth to turn up its built-in reverb.
For audio tracks in RealBand, there's no dedicated Reverb knob, just Aux 1, Aux 2, etc.
This'll work: Open the mixer, and on the right side, near the top, you'll see the Aux return channels, A1-A8, each with a Send and Ret knob. Click the FX button above A1, and the DirectX/VST Window will appear, with Aux1 selected in the Track drop-down menu.
Select PG Reverb in the first drop-down menu under Plugin, move the Mix slider all the way up to Wet, and then turn up the Aux knob on any audio track that you'd like to add reverb to. You can then adjust the other sliders on the PG Reverb control panel to taste.
Hope this helps!