Three things ...
1) And this is the main problem: You are trying to access the DIV with ID "newachievementdiv" outside of the $(document).ready() callback. So this DIV might not be ready yet
2) There is no event handler for mouseover ... so how should your program know that it should send something on mouseover?
3) You are already using jQuery, so you should not use getElementxxxxxxxxxx methods but rather the respective jQuery methods like