GetItemTransactions or GetSellerTransactions return TransactionID '0'

Answer: When an item is listed as a Chinese auction type ( the default value of the AddItem.Item.ListingType property), the TransactionID always returns a value of '0' as described in the online document : http://developer.ebay.com/DevZone/XML/docs/Reference/eBay/GetItemTransactions.html

"For Chinese auctions listings (single-item listings for which there can be only one transaction), TransactionID is always 0 ..."

TransactionID is returned in several APIs : GetItemTransactions
GetSellerTransactions
GetOrderTransactions
GetOrders
GetFeedback
GetItemsAwaitingFeedback