controls are not working

i tried some different control setups and one of them does not do what it has to do my forward key was W my left key was Q my crouch key was R my right key was E so when i do W E and R togheter it does what it has to do however when i do R W and Q it is always missing one key like if i press W first Q second and at last R it does not give me crouching effect etc...