One of my page is not works well on Internet Explorer while perfectly works on other browsers such as Firefox, Opera, Safari, Google chrome.

The page what i mention above is Web Diagnostic For WebMaster

The 1st problem is come from Google Analytic Java Script.
IE said "Error: '_gat' is undefined
complete script for GA is
var pageTracker = _gat._getTracker("UA-958897-7");

The 2nd problem is when i click on the botton to proceed with web analysis.
IE bring back to the blank form without any error message.
I suspect it something like undefined runtime error

Please advise what i must do for Internet Explorer