Queries :: Query Parameter Input On A Form (combo Box)

I have a table which holds information on audits that have been carried out on staff member's actions. The 'Supervisor' field is populated via a combo box which is linked to a separate table (tblSupervisors).

I am now trying to build a query to allow me to extract all audits that have been carried out on a specific supervisor - rather than the criteria to be [Enter Supervisor Name] and allowing text entry, I thought it would be better to have form that pops up with a combo box that is used to select the supervisor (from tblSupervisors);

So far:

- Form "Supervisor_Select" is created, and has a combo box that looks up from tblSupervisors

- Macros as specified in the instructions are created (Open Dialog, Close Dialog, OK and Cancel)

- Query is done, all bar the criteria expression on the desired field.

- Module is created as described in the instructions, and is called "Supervisor_Select"

I have tried putting the following in the criteria;

[Forms]![Supervisor_Select]![cboSupervisor], however I think I am missing the bit where the query opens the "Supervisor_Select" form?? Will this only work from a button where the on click event runs the 'Open Dialog' macro and then runs the query?