Hi:
Well, it could be one of several reasons. You said you are forwarding your Google Voice number to a PhonePower number. Call that PhonePower number directly, from some other phone number (like a mobile phone number or traditional land line number). What happens?
The "Chat" option isn't needed in your scenario, because you want to instead forward inbound calls to PP, not to Chat. FYI, the Chat setting is still available, in the "Legacy" Google Voice settings page.
Look at your OBi 200's settings on the OBiTALK dashboard. Does it say that the Service Provider (SP1 -- SP4) that you are using with Google Voice is "Connected"? If so, attempt to make an outbound call from that SP. Does it work? If so, does the called party see your Google Voice number as the caller ID, or do they see a blank field or "unknown caller"?