Why can't i ever steal the ball in fifa11 online for ps3?

i wanna start by sayin that i was always crazy good at fifa, i have been playin since 03. but since i couldnt afford a ps3 till recently im new to fifa11...i picked it up fast but when i play online, i can NEVER steal the ball from whoever im playin,(i play as r. madrid, or m. united) my players just run behind him while he runs at goal and puts one in the back of the net, meanwhile when i finally actually get the ball its gone no problem. also the same with headers, if its a cross or a corner im screwed they're going to score on me! what the hell is going on?!?!?! and when i shoot the goalie is always stoppin them, no matter how good i place my shot...now sometimes i play and will win 5-0, i've heard of people cheatin online but do u think thats whats going on here? please sombody help me!