Ajax.Request doesn't work in IE

I using prototype javascript

I am using ajax function which works perfectly in FF but not in IE

var MOList_VenuePostBox;

function getPreSearch(tid,tname){

include_js("http://" + getHostPath() + "/_scripts/lib/z_autocomplete_messagecenter.js",
function() {
            //,{fetchFile:'/ajax/spot/getmyspots.aspx'}
        MOList_VenuePostBox = new MOList('txtTagTheItem_VenueProfile', 'molist-auto1'); 
        var counter = 0;

        // fetch and feed
        new Ajax.Request('/_service/getTagwordsByName.ashx', {
            onSuccess: function(transport) {
                transport.responseText.evalJSON(true).each(function(t) 
                { 
                    MOList_VenuePostBox.autoFeed(t);
                }开发者_开发百科);
            }
       });                                                                                  
});
}

Thanks in advance

I just passed method as get

it solved my problem

include_js("http://" + getHostPath() + "/_scripts/lib/z_autocomplete_messagecenter.js", 
function() { 
    //,{fetchFile:'/ajax/spot/getmyspots.aspx'} 
    MOList_VenuePostBox = new MOList('txtTagTheItem_VenueProfile', 'molist-auto1');  
    var counter = 0; 

    // fetch and feed 
    new Ajax.Request('/_service/getTagwordsByName.ashx', { 
        method:get,
        onSuccess: function(transport) { 
            transport.responseText.evalJSON(true).each(function(t)  
            {  
                MOList_VenuePostBox.autoFeed(t);
            }); 
        } 
    });             
});