Have you tried pouring some water into the canister first?
The Rena Filstar priming method works with Fluval filters. Simplified, it is to start with an empty filter - no water in it. With the hoses disconnected from the filter, fill the inlet hose with water all the way to the top. Plug in the hoses and with the inlet and outlet hoses in the tank as they normally are, and the water trapped in the inlet hose will drop rapidly into the filter, sucking water up over the top of the tank, establishing a siphon. Wait while the filter fills with tank water - you will hear the flow, so when it stops the filter is full. Now turn on the filter and it should work fine. If it hesitates, then use the prime plunger briefly. I have done this twice and it worked well.
You're a genius! Tried everything and my two year old 206 would not prime. Turned it upside down...Viola!!!! Thank you SO MUCHTry turning it upside down then slowly bring it to an upright position, you should see the air bubbles that were trapped inside the canister exiting thru the outlet.