Ajax响应问题

I'm handling a very (VERY) simple ajax error, but I cannot manage to fix it:

I have the following structure:

• \manager\javascript\ajax.js
• \manager\manager.jsp
• \manager\test.jsp

In my ajax.js file I have a VERY simple function (without parameter, to make things easier)

function makeAjaxRequest() {
   http.open('get', 'test.jsp');
   http.onreadystatechange = processResponse();
   http.send(null);
}

function processResponse() {

   alert("Ready State: " + http.readyState);

   if(http.readyState == 4){
       var response = http.responseText;
       document.getElementById('ajaxResult').innerHTML = response;       
   }
}

And finally, my test.jsp file contains only:

<% out.print("JSP result");%>

In my manager.jsp I call the function but I receive only one "alert" from the processResponse with readyState = 1...

For sure there is something I'm missing in some step.

Could you help? Thanks a lot.

Cheers, Lucas.

EDIT

For sure in my ajax.js file there is also the function to get a xmlHttpObject.

This line is wrong

http.onreadystatechange = processResponse();

Remove the () to assign the actual function, not the result of the function.