screenx/y() bug?

[CheeToS2]

Ok. I'm trying to use screenx(x,y) & screeny(x,y) to display 3 images above an npc precisely (pixel-wise), and i'm experiencing 2 problems.
1) It doesn't work serverside
2) It returns negative values, even when the x/y I specified is clearly in my screen range.

Im also using setshape2 if it matters.

EDIT: strange, it only shows it incorrectly when its used in the if created event, I used it in a timeout loop & the numbers were correct @_@.