listbox help

I need help. I am programming a client/server app that uses a listbox and a betrieve database to display data. When an Item in the listbox is clicked I

need to pull up the record that matches. All Items have the same
ID number b/c they are all items on the same order (thats why they are in the list box). I think that i need to use the listindex

property and assign it to an array for all the key values as the listbox loads up, then I can check for equality on the listindex property. I cant seem to get the syntax right. any suggestions or ideas are welcome.
please respond

urgent
thanks........