CRM 2011 Online Prompting Credentials Entry for Odata Query

Hello all,

I'm in the process below of trying to learn how to use Odata by making a simple request for data from another entity within my CRM 2011 online environment. I have two problems though they may be related.

1. When I run my below code, as soon as the XMLHttpRequest retrieveReq uses its send() function, internet explorer (and also Firefox and Chrome) prompt me for a username and password. Given I'm already logged in I don't understand why this would happen and I can't seem to find any articles that explain how to fix this.

2. My second problem is that if I simply click cancel or enter some user information to get past the credentials prompt, I then get the javascript error " Invalid character, character 9" on the line  "var retrieved = JSON.parse(retrieveReq.responseText).d;" in the below solution which again I don't understand why. 

Also the function tryRest() below is triggered when I select a value from a lookup field "new_certificate".

I'm quite new to this stuff so all your help is appreciated. Thanks in advance! 

function tryRest() 
{	
    var serverUrl = document.location.protocol + "//" + document.location.host + "/XRMServices/2011/OrganizationData.svc";
    var newCertificateid = Xrm.Page.getAttribute("new_certificate").getValue();
    var newCertificateid = primarycontact[0].id;
	var newCertificateid = newCertificateid.replace('{', '').replace('}', '').toLowerCase();

 // Creating the Odata Endpoint
    var oDataPath = serverUrl 
    var retrieveReq = new XMLHttpRequest();
	var Odata = oDataPath +   "/new_certificateSet$select=new_CertificateClassSUFFOLk&$filter=new_certificateId eq guid'"+newCertificateid+"'";

    retrieveReq.open("GET", Odata, false);
    retrieveReq.setRequestHeader("Accept", "application/json");
    retrieveReq.setRequestHeader("Content-Type", "application/json; charset=utf-8");
    retrieveReq.onreadystatechange = function () { retrieveReqCallBack(this); };
    retrieveReq.send();
}

function retrieveReqCallBack(retrieveReq) 
{
    if (retrieveReq.readyState == 4 /* complete */) 
	{
        var retrieved = JSON.parse(retrieveReq.responseText).d;
        var output = retrieved.results;
		// Alert the output from new_certificate object. Note I've yet to configure this - the program won't get here currently. 
        alert(output);
     }
}