Hi Paul,
The method you are using can return more than one result, so you will need to foreach through the ObjectQuery set:
foreach (var sku in skus)
{
int skuID = sku.SKUID;
...
}
Or modify the result to return the first match:
var sku = SKUInfoProvider.GetSKUs().Where("SKUNumber", QueryOperator.Equals, SKUNumber).FirstResult().FirstObject;
int skuID = sku.SKUID;