authenticating Planet ocean and odd Seller response.

I recently purchased an Omega Seamaster Planet Ocean (Ref. 215.30.44.21.01.001) from a reputable seller on Chrono24 .The Master Chronometer certificate provided with the watch includes a serial number and access code, but when I enter the information on Omega’s official website, it returns a message stating that no results could be found. I texted the seller and his response seems strange to me, should I think about contacting chrono24 to start the refund process if I can’t authenticate the watch?