Keyboard and mapping not working on my PC

[game addict]

hello guys, am new here.
i have a serious problem with my ppsspp. my fav game is pes soccer but am unable to enjoy it because of keypad problem, the problem is i can't press some keys together at the same time, when i do such keys will be automatically untouched after some seconds of pressing them even though my hands are still on them , it's hard to explain though e.g if i want to cut into opponets box from side , it requires to press running key R1 with dpad diagonals but when i make such combination the keys will be unpressed even though my hands are still on them thereby making the player to stop