A very strange problem about when callback funtion was executed

I got a very strange problem that I coulnd't understand. I got a pageinit js function, in this function I accessed some page methods to get some values stored in sesstion. Then after getting those session values, in my pageload function, I passed them to local web service.  The problem occured here:I got a alert in my javascript pageload function just for test purpose. I found that everything worked fine if I had this alert in the begining of my pageload function. all values that are stored in the session were retrieved before page was loaded and therefore the call to web service were executed and returned everything that I want.

However, the very strang thing was that after I commented out the alert in my pageload, it seemed that the callback function onSucceeded was not called before pageload function, therefore, the code didn't get the values(instID,VK and loginPath) from session and the call to the web service was failed because the para ...