Set values from one entity to another

Hi

i am trying to populate some values on the 'new free text item' screen onchange of selecting a product, i have the following code in the custom content:

function setValues()
{
var prodId = crm.fields("quit_productid").val();
var successProduct = function (crmRecord) {
prodCode = crmRecord.prod_code;
crm.fields("quit_sku").value(prodCode);
}
crm.sdata({
entity: "newproduct",
id: prodId,
success: successProduct
});

and then calling this function onchange of the product field but cant get it to work, can anyone spot anything wrong with the code?