asp.net 2.0 callbacks operative justly firefox

i've implemented .net web control uses callback structure implemented asp.net 2.0. it's an autodropdown control, works justly ie 6.0/7.0 google chrome. here's applicable callback function:

function receiveserverdata(args, context)
{
document.getelementbyid(context).style.zindex = 300;
document.getelementbyid(context).style.visibility = 'visible';
document.getelementbyid(context).innerhtml = args;
fixhover(context);
}

in firefox, "args" always same data, innerhtml <div> arrangement dropdown always shows same items. i've doublechecked client-side code, right information being sent client->server relapse server-> client.

of note, "webform_docallback" duty combined .net framework, following dash removing called:

if (setrequestheadermethodexists) {
xmlrequest.onreadystatechange = webform_callbackcomplete;
callback.xmlrequest = xmlrequest;
xmlrequest.open("post", theform.action, true);
xmlrequest.setrequestheader("content-type", "application/x-www-form-urlencoded");
xmlrequest.send(postdata);
return;
}

and callback duty receiveserverdata called both xmlrequest.open("post", theform.action, true); xmlrequest.send(postdata);. i awe causing an error, nonetheless i'm during finish debugging skills.

edited supplement -- receiveserverdata being called twice unequivocally initial i dropdown -- fact, dropdown works justly unequivocally initial keystroke. stops working, doubles callback aged relapse data, after initial keystroke.