Prototype. js Ajax cannot retrieve XML in Firefox ??? -* (￥-· (￥ ...... *...... $ -*(!!!

The Code is as follows:
<SCRIPT type = "text/JavaScript" src = "../scripts/prototype. js"> </SCRIPT>
<SCRIPT type = "text/JavaScript" src = "../scripts/transferxml. js"> </SCRIPT>
<SCRIPT type = "text/JavaScript">
// Global variable
VaR progressbar; // progress bar

Window. onload = function ()
{
// Load the list of organizations
Getbranchlist ("");
}

/*-------------------------------------------------------
Function: List of organizations
--------------------------------------------------------*/
Function getbranchlist (ID)
{
Progressbar = new progressbar ();
Progressbar. isneedprogressbar = true;
Progressbar. setstatus ("loading organization data ....");

VaR url = '../branch. Do ';
VaR pars = 'Action = getbranchlist & branchid = '+ ID;
VaR myajax = new Ajax. Request (
URL,
{Method: 'get', parameters: pars, oncomplete: getbranchlist_callback}
);
}
/*-------------------------------------------------------
Function: Organization list-callback Author: dengchunming
--------------------------------------------------------*/
Function getbranchlist_callback (originalrequest)
{
VaR objxml = originalrequest. responsexml;
Alert (originalrequest. responsetext); // for the first time, it is no problem to retrieve the list. Click "retrieve sublist" and the data will not be available. You can be sure that the background program has returned XML, but prototype. JS not received !!!!!
// Resolve the XML to divbranchlist
Displaytransformedxml (1, objxml, "../XSLT/admin_branch_list.xsl", document. getelementbyid ("divbranchlist "));
Progressbar. Close ();
}

</SCRIPT>

// There is no problem in IE. For the first time in Firefox, there is no problem in retrieving the list. If you click to retrieve the sublist, no data will be obtained. You can be sure that the background program has returned XML, but prototype. JS not received !!!!! Does anyone know why?