the filter would be something like
"[Age]='" & Me!cboAge & "' AND [LastName] LIKE '*" & Me!LastName & "*'"
And you do need to decide whether you want AND or OR.
looking for someone who is 35 and has a last name of 'Smith'
will produce different results to
looking for someone who is 35 or has a last name of 'Smith'
you probably want to do you code slightly differently as well and assign to a filter string before opening the form e.g.
Code:
Dim FilterStr as String
If IsNull(Age) = False Then FilterStr="[Age]='" & Me!cboAge & "' AND "
If IsNull(Ethnicity) = False Then FiltrStr=FilterStr & "[Ethnicity]='" & Me!Ethnicity & "' AND "
...
...
If len FilterStr>0 then
Filterstr=left(filterstr, len(filterstr)-5)
DoCmd.OpenForm "Actor Search", , , FilterStr
end if