WHIP stream to Amazon IVS

[thebrooktrout]

I created an IVS stage and publish token. I want to publish to the stage using OBS. Using Stream Settings, I choose WHIP. The server is the WHIP endpoint given in the AWS console for IVS realtime streaming. I copy the publish token and paste into the Bearere Token field in OBS settings. I hit Start Streaming. I get immediate error: "Could not access the specified channel or stream key, please double-check your stream key. If it is correct, there may be a problem connecting to the server. "

Any ideas on what I'm doing wrong? Thanks.