Help request [First time game loading]

[Zeralux]

So I have the .ISO file for the game I wish to play, and PPSSPP (v 1.22) detects it, I open it. But an error message pops up.
It reads:
Could not load game. Could not find executable disc0:/PSP_GAME/SYSDIR/BOOT.BIN

Am I getting this message due to the fact that the ISO file I used is broken or faulty?
Or because an extra step is required in playing games on PPSSPP?

PS: I'm almost certain that it cannot be the latter, as, according to the official PPSSPP help page, I just need to download an ISO and load it. Simple.

Please help.

---

Nevermind, figured it out, it was the iso file.