set currentcost of product

Hi experts.

I am currently working on a project that intends to set product data in CRM, using our ERP database as a source.

Querying ERP and getting the correct data into c# is no problem.

Setting CRM product fields "name" and "price" has also succeeded.

I know want to expand the data transfer to the fields currentcost and standardcost for entity product. However, I am getting "Object reference not set to an instance of an object".

Here is a bit of code i use:

QueryExpression qe = new QueryExpression();

qe.EntityName = "productpricelevel";

qe.ColumnSet = new ColumnSet();

qe.ColumnSet.Columns.Add("amount");

qe.ColumnSet.Columns.Add("productid");

qe.ColumnSet.Columns.Add("pricelevelid");

EntityCollection ec = ct.RetrieveMultiple(qe);

foreach (Entity act in ec.Entities) {

EntityReference reference = (EntityReference)act["productid"];
Entity prodEntity = ct.Retrieve(reference.LogicalName, reference.Id, new ColumnSet("productid", "productnumber", "price", "name", "currentcost", "standardcost"));

//The following line is working fine:

 prodEntity.GetAttributeValue<Money>("price").Value = decimal.Parse(glListPrice);

//the next line is NOT:

 prodEntity.GetAttributeValue<Money>("currentcost").Value = decimal.Parse(glListPrice);

}

ct.update(prodEntity);

I am almost certain the queryexpression "qe" isn't retrieving the currentcost field, but how can I convince it to retrieve it?

Thanks