data to a grid

I am about at wits end, I hope someone can help me here.

What I am trying to do is create a small flash rss feed that feeds into a dataGrid, where you can link on the topic to go directly to that URL. There is a ComboBox that lists all the different topics to choose from and a button to activate it.

I have binded the XMLConnector to the ComboBox, dataGrid, and button. I am having the worst time creating a variable that will change the URL.

When I go into the bindings area of the Component Inspector, it asks for a URL. When I put a URL there, that URL will populate the dataGrid, but then changing the ComboBox does nothing.

I figured the way to do it would be do create a variable in ActionScript that would change depending on which ComboBox item they chose. But I can't seem to get that to work. I blanked out the URL area in bindings and put the followiing in ActionScript:

import mx.controls.*;
import mx.containers.*;
import mx.controls.gridclasses.DataGridColumn;
import mx.data.components.XMLConnector;

var rss_cb:ComboBox;
var myDataGrid ataGrid;
var myReceiveXMLConnector:XMLConnector;

form = new Object();
form.change = function(eventObj){
trace("Value changed to " + eventObj.target.value); //this works just fine
}
rss_cb.addEventListener("change", form);

if(eventObj.target.value != "Authorware"){
myReceiveXMLConnector.URL = " http://www.macromedia.com/go/rss_authorware"; //this does nothing!
}

myReceiveXMLConnector.trigger();

I have changed the code so many times and tried so many different ways, that I can't think anymore. What am I doing wrong?