Animations not playing as animated?

So what I mean by this is that if i animate an arm to be in this position and here, it will be in the position but slightly to the side or down etc.

I am animating with additions to the character's 'skeleton' which means the tool is part of the character.

It looks fine when I play it from the animation editor but in actual gameplay (studio AND normal servers) the animation is wrong.

Could anyone think of a reason as to why this is happening?