What needed to do before use fields in a table

Hi all,

After I set form' s record source to a query, what else shall I do before
using fields from the query.Something strange happen here, there are three
combs on my form, they are all bound to the fields of a same query, at the
same time they all have their own row sources which are three query, in
comb1' s change event , two other field1 and field2 are assignment to comb2
and comb3 to affect the default selection, but field1 and field2 are not from
the qury in comb1's row source.
I hope I make it clear.
Could you tell me why?

Clara
thank you so much for your help