Not sure which Rebug you are using, or which model console? But that PS2 Emu toggle is not needed on Rebug 4.85 and even on older versions it was only needed on some console models. If you are on Rebug 4.85 Make sure you have the latest toolbox installed.
Make sure your webMAN Mod is up to date too, install this an then run it.
OK, Rebug 4.84 still uses that PS2 emu option, but its not needed on a CECH2101 afaik. You could try using Managunz to mount the iso, just to rule out any possible webman mod issue with that game.