ms access - Show all records in a list box -

i'm making database records teachers , students , when scheduled have lessons. have list box taking data query being filtered combo box taking data table.

the filter working there no way display records query.

is there way add option combo box pull records query through list box instead of filtered few?

ps. preferably using embedded macros, vb if necessary

the row source of combo box ('teachers' table):

select [teachers].[teacherid], [teachers].[forename], [teachers].[surname]  teachers  order [surname], [forename], [teacherid]; 

the row source of list box ('todaylessons' query, 'teacherid' using criteria of combo box on form):

select [todaylessons].[lessonid], [todaylessons].[slotid], [todaylessons].[lesson date],         [todaylessons].[lesson time], [todaylessons].[teacherid], [todaylessons].[studentid]  todaylessons  order [lesson date], [lesson time], [teacherid]; 

row source causing problem (i've tried adding 'from teacher' before 'union'):

select -99 teacherid, "* *" forename, "" surname union select [teachers].[teacherid], [teachers].[forename], [teachers].[surname] teachers order [surname], [forename], [teacherid]; 

if want use listbox, can this:

combobox, adding "all" selection union query:

select -99 teacherid, "* *" forename, "" surname union select [teachers].[teacherid], [teachers].[forename], [teachers].[surname]  teachers  order [surname], [forename], [teacherid]; 

listbox:

select [todaylessons].[lessonid], [todaylessons].[slotid], [todaylessons].[lesson date],         [todaylessons].[lesson time], [todaylessons].[teacherid], [todaylessons].[studentid]  todaylessons  (teacherid = forms!yourform!cboteachers)    or (forms!yourform!cboteachers = -99) order [lesson date], [lesson time], [teacherid]; 

the "or" part of clause makes records true, if special entry of combobox selected.

-99 arbitrary number, if teacherid autonumber, can use 0 instead.