file upload using dojo.io.frame.send doesn't work in IE the first time

I'm trying to do an ajax file upload using dojo.io.frame.send(). It works with FF and chrome without any issues but not in IE 8 (not sure about other versions). The code is pasted below:

function submitForm()

{       

dojo.require("dojo.io.iframe");

dojo.io.iframe.send({

    url : "/uploadfile.do",

    form : "myForm",

    method: "POST",     

    handleAs: 'text',

    load : function(response, ioArgs) 

    {

        return response;

    },

    error : function(response, ioArgs) {

        return response;

    }

}); 

return false;

}

I searched on the web and found this:

http://groups.google.com/group/dojo-interest/browse_thread/thread/17dace02652bcec3

which prompted me to add the following snippet after dojo.require() line in the above code:

if ((dojo.isSafari || dojo.isIE) && dojo.io.iframe["_frame"])

{

    dojo.destroy(dojo.io.iframe['_frame']);

    var frameName = dojo.io.iframe._iframeName;

    dojo.io.iframe["_frame"] = window[frameName] = null;

    if (window.frames)

        window.frames[frameName] = null;

}

With this it doesn't work in IE the first time but works when I click on the upload button the second time.

Additional info: My form tag in HTML has method="post" parameter.