No Records Found Popup

I have a database that holds hardware data. It's working fine, but there's a slight itch I'd like to scratch and I'm not sure how.

Very simply, I have a table listing printers. I have a search form with combo boxes called 'cboRoom' and 'cboDepartment'. The room and department fields in the printers table are lookups to a room table and a departments table respectivley.

The search form works fine by using the combo boxes to select a room and/or department, click search, and a query is run using the combo box selections as parameters. The query is also made to show all records if the combo boxes contain null. A form is then displayed with the query results.

Say for example, we have a room called B24. If B24 is selected in the combo box and the query run, I want a popup to appear that says 'No data with these search parameters' if there are no records containing 'B24'.

The search button (which is actually a label for design reasons) on the search form currently does nothing more than this;

Private Sub lblSearch_Click()
DoCmd.OpenForm "frmPrinters", acNormal
DoCmd.Close acForm, "frmPrinterSearch"
End Sub

'frmPrinters' is obviously using the query (qryPrinterSearch) as its recordsource. Obviously, the popup needs to appear as soon as the query has been run, but I'm not sure what code to use or where to put it...

I know I need some sort of (pseudo)

If frmPrinters.cboRooms Is Null
MsgBox "No Data"
Close frmPrinters
Open frmPrinterSearch
End If

Something like that. But obviously I need to do it for both cboRooms and cboDepartments, after the form has attempted to populate itself with data from the query (otherwise it return null values anyway I guess).

Any help with the code and where to put it much appreciated.

Regards,

Steve Swallow