When you make a Sales Invoice with multiple articles + 1 item charge item and you assign the item charge to the different items, an item ledger entry is created for each item with the related charge, but dimension values are empty. I use Dimension 1 for productgroups and every article is assaigned to a productgroup value.
If I want to calculate the costs by Productgroup, I will miss the item charges because no Dimension value was linked in the item ledger entries!