Double skin facade

[moowaaan]

Hi guys,
I've got a problem as making the 1 m wide cavity double skin facade.
since in create a room for the cavity and assign as "glazing cavity" with "1" air change
Then, fill the outer surface with 100% 6mm single glass.And its not working.

My question is "does assigning the glazing cavity profile create the nat. vent automatically?"
If not, do I have to make two holes/openings, one on the top and another on the bottom of the outer pane?
and applying it with Macroflow? or any recommend?

Cheers,

Pisut