Pull Info from Related Record in CRM 2011

function Form_onload(){
var store = Xrm.Page.data.entity.attributes.get("new_store").getValue();
if (store != null)
{
var new_storeid = Xrm.Page.getAttribute("new_store").getValue()[0].id;
var retrieveResult = null;
retrieveResult = CrmServiceHelper.Retrieve("new_store", new_storeid, ["new_tax"]);
Xrm.Page.getAttribute("new_tax").setValue(parseFloat(eval(retrieveResult.attributes.new_tax.value)));
}
else if (store != null)
{
Xrm.Page.getAttribute("new_tax").setValue(0);
}
};