Small Trick on IE7 with Ajax

Below is a javascript I wrote for Ajax call few days ago. This code run smoothly in Firefox, IE7 first call success, second call onward all fail.

Do you see what wrong on the above code? This code took me half day to debug, I was thinking is it IE7 browser bug or what. But in fact, the main reason it fail on IE7 is because IE7 make Ajax call very fast from second call onward.

The code haven't reach the set loading part already finish set result. Mistake learned.