Friend's Username/Password Invalid but when I copy/paste it on my laptop, works fine.

So my friend recently made a league of legends account, he had started playing the previous day and it was working fine. But as of today, his username and password wasn't working on his laptop. He changed his password twice. He told me his credentials (He is my best friend) and I logged in fine on my laptop. He then screenshared me on skype, copied and pasted the username and password onto the launcher, and it still didn't work. He had downloaded the game from the League of Legends website and he could log in there too. Please help me because neither of us have any idea why this won't work.

His in-game name is ShadowAF