Scripting with shippingcost and handlingcost

I need to seperately export the shipping cost and handling cost for each of my products. I tried to perform a saved search but shipping cost and handling cost are not provided as result columns. As a solution I created a quick suitelet to perform this task, since shippingcost and handlingcost appear to be scriptable records on inventoryitems according to the documentation.

I get the following error:

"An nlobjSearchColumn contains an invalid column, or is not in proper syntax: shippingcost."

function demoList(request, response){    
var list = nlapiCreateList('Shipping Cost List');    

list.addColumn('itemid','text', 'Item Name', 'LEFT');
list.addColumn('shippingcost','currency', 'Shipping Cost', 'LEFT');