Hi
I'm not sure I understand your question 100%, but if I understand it correctly, you want to select a value from a listbox on a form. The value in the listbox is passed through to a query as the criteria for a certain field.
If that is the case, then in your query design screen, under the column heading that you wish to set the crtieria for, enter criteria using the following syntax:
[Forms]![YourFormName].[YourListBoxName]
Check you have the correct syntax, the correct form name and the correct name of the list box.
If I have mis-read your question, post a reply with some more information.
HTH, Andrew