I am building a simple database for my cross-dock warehouse. That is, unlike the warehouse of a retailer, my warehouse don't store the same products over and over. Instead, each time we receive a shipment, we assign a dock receipt number to it, and we use the dock receipt number as the ID of the shipment. Once we ship it out from our warehouse, we never use the number again. Thus, I want to eliminate the dock receipt number from the list box on my 'shipping' form once it is selected. My database is working alright, except the list of of dock receipt number gets bigger and bigger, by showing unnecessary candidates.