MS CRM 2011 online - setting appointment's set regarding field automatically

I have a form where is a subgrid pointing to appointments. When I add appointment via the subgrid, I want to set the appointment's regarding field to populate automatically and pointing to originating entity.

function EventOnLoad()
{
    // is this a create form?
    if (Xrm.Page.ui.getFormType() == 1)
    {
        // The query string has the parent's id and object type code
        var queryStringObject = Xrm.Page.context.getQueryStringParameters();

        if (queryStringObject != null)
        {
            // let's go get the event's object type code.  
            var eventOTC = getEntityOTC('mpxrm_project'); 
			alert("stage 1");

            // If the parent is an event, then we need to set the regarding object.
            // NOTE: If this appointment was created from the left navigation _CreateFromType will be null and the code won't execute (which we want)
            if (eventOTC == queryStringObject._CreateFromType)
            {
                var eventName = "";
				alert("stage 2");
				var root = Xrm.Page.context.getClientUrl();
				alert(root);

                  var sQuery = root + "/XRMServices/2011/organizationData.svc/mpxrm_projectSet?$select=mpxrm_name,mpxrm_project_id&$filter=mpxrm_project_id eq guid'"+ queryStringObject._CreateFromId +"'";

            alert("stage 3");
				alert(sQuery);
				var request = new XMLHttpRequest();
                request.open("GET", sQuery, false); //sync
                request.setRequestHeader("Accept", "application/json");
                request.setRequestHeader("Content-Type", "application/json; charset=utf-8");
                request.send();

                var retrievedData = JSON.parse(request.responseText).d;
				alert("stage 4");
				alert(retrievedData);
                if (retrievedData.results[0].mpxrm_project_id != null)
                {
				alert("stage 5");
                    eventName = retrievedData.results[0].mpxrm_project_id;

                    var olookup = new Object();
                    olookup.id = queryStringObject._CreateFromId;
                    olookup.entityType = 'mpxrm_project';
                    olookup.name = eventName;
                    var olookupValue = new Array();
                    olookupValue[0] = olookup;

                    Xrm.Page.getAttribute('regardingobjectid').setValue(olookupValue);
                } 
            }
        }
    }
}

// This funtion gets the Object Type Code for any entity
function getEntityOTC(entityName)
{
    var lookupService = new RemoteCommand("LookupService", "RetrieveTypeCode");
    lookupService.SetParameter("entityName", entityName);

    var result = lookupService.Execute();
    if (result.Success && typeof result.ReturnValue == "number")
    {
        return result.ReturnValue;
    }
    else
    {
        return null;
    }
}

I managed to get this on alert("stage 4");. Then I managed to get this to alert(retrievedData); but with this i get answer undefined.

After that I get error message:

There was an error with this field's customizes event.
Field:window
Event:onload
Error: unable to get property 'results' of undefined or null reference

Any helps. This is working on another environment where only fieldnames and entity's name are different.