Keep rejecting “We are having trouble starting or finding your opened game”

Hi all,
I’ve tried installing wemod by following instruction on this link
https://youtu.be/k_iIWjYXGO0

However when I add the game.exe (the one I’m trying to play is Aliens: Dark Descent ), it keeps rejecting “We are having trouble starting or finding your opened game”

I then found the trainer post and add the game from another path, still no use at all

Could some expert please teach me how to fix this please? I’m really eager to play this game

Many thanks

Unfortunately, we cannot offer any assistance for this issue, as Steam Deck is not something we offer support for at this time. I will leave this thread open, so if someone else using it on Steam Deck has an idea, they can reply.