I am following all steps in the video MSFS A310 Tutorial 2: FMC Setup | Real Airline Pilot. It all worked exactly as shown except right after finishing flight plan entry at 06:32 in the video he clicks on INIT then NEXT PAGE. He gets a page to enter weights, CG, etc. When clicking INIT then NEXT PAGE I don't get a next page at all, I only get NOT ALLOWED at bottom of the screen and no change to anything else on the screen (still showing flight plan). So I can't proceed to calculate anything in the performance.
I tried this several times in FS2020 and FS2024 - same problem occurs. I have searched Inibuilds and FlightSimulator.com but to no avail. Any suggestions appreciated.