ppsspp says all game are corrupted

[goten9]

Hi I'm trying to use ppsspp on smarthphone a52s with latest version of android, every time I try to play a game ppsspp say tha the iso is corrupted.
I tryed with gang of london Metal gear solid peace walker and portable plus, but all the time ppsspp says is corrupted, i tryed the same version of this games importing them from my smarthphone into my pc, and when i used them with ppsspp they are all working.
I think i do something bad on my smartphone maybe, something that prevent ppsspp to access file explorer?

sorry for my bad english
thx for the help