[GAMEPLAY] Can't set ALT+1 as leveling first spell up

I have my own spell up setting in the game. I like to level them up at ALT+1, 2, 3, and 4. few days ago, ALT+1 won't work anymore, but ALT+2,3,4 are still fine, and casting spell 1 is fine as well. I thought that might be a problem of my keyboard. So I tried that same thing on China Server of League of Legends, and that is fine. It bothers me a lot during the game, and this habit is too hard to change. So please help me fix it, thanks a lot.