ProductListingDetails null on eBay API GetItem Call

I’ve recently been working with the eBay API trying to get orders and their item details. In the API documentation it tells you you need to specify the DetailCodeType to get the ProductListingDetails.

http://developer.ebay.com/devzone/xml/docs/Reference/eBay/GetItem.html

The ProductListingDetails object contains Brand, Model, MPN, among other things I need, but it always returns as null. Even though I have that data set in the item listing. This is an issue on both the live site and their sandbox environment.

Has anyone else ran into this issue and know of a solution where I can get these details using the eBay API? My code is below:

public static ItemType GetItem(string itemId)
{
    GetItemCall itemCall = new GetItemCall(apiContext);
    itemCall.DetailLevelList.Add(DetailLevelCodeType.ReturnAll);

    return itemCall.GetItem(itemId);
}