PayPal not show items with price $0.00
I just went live with a new website using eCart and PayPal Standard. I am successfully running transactions through PayPal with one exception. I have items that have zero dollar amounts included with the buyer's order. These items are displayed and stored properly within eCart but when the invoice is sent to PayPal (i.e. 4 items selected for purchase, 2 are priced at $0.00) only the items with a dollar amount are shown on PayPal's order summary page.
Is this a PayPal problem or do I need to change something to allow the zero dollar items to be sent to PayPal? PayPal say this scenario works when using there invoicing.