Don't really understand the custom search

I wanna play map A,B,C with mode D

I still get a match but it's not map A,B,C and not mode D so I quit out the game and try again, rather just wait till it does find one, I am putting custom search for a very good reason

Might take an extra minute or 2 but if I get the wrong map and mode it takes another 2 mins to wait, enter, quit and re-try......