MouseMove Moves Mouse In Windows But Not In Game...

This is a java application and I have been having this problem with another programming language so I decided to re-program the whole thing hoping it would work in java but i get the same problem. Heres the problem...

I want to move the mouse in a FullScreen game to a specified coordinate. On windows it works fine and moves the mouse, but when I go into the game it moves the mouse, but in some random direction like straight up, or straight down. What is causing this problem? Its driving me nuts and I have wasted way way to many hours trying to solve this! Thanks Alot!

No idea what you mean by "on Windows" here, or how that's different from "in the game" -- can you explain this to me? Also, of course, without seeing at least some of your code, there isn't much chance we'll guess what's wrong with it.

By on windows I mean like on the desktop or regular stuff that uses the normal cursor. The game uses a seperate cursor which I have to control but cant. Its not my code thats a problem, its whether there is a command that can move the game cursor to the coordinate specified rather then screwing up somwhere along the way. I think the game has a different coordinate system which is why its doing this. Im trying to use mouseMove(x,y) which dosent seem like a good way to move the game mouse.