Cubase wont play any sound on external 8-channel Interface

Hi, I got this problem where any of the 2 external 8 channel Audio interfaces wont play sound through cubase(artist 7.5.40) but can play audio files on my mac10.11

These interfaces are Presonus audiobox 1818 & Focusright scarlet 18i20 2gen,
both these interfaces has their own mixer control application.
I can set any of these interfaces as default outputs on my mac and audio files will play as usual. But when i open Cubase Artist 7.5 and got either of them setup in device setup and VST connections, nothing happens… if i add an midi instrument and play with the virtual keyboard, even the meter on the instrument track gives no output. or if i add an audio file to the project, the audio track doesnt show any signal. it seems like cubase just wont allow any sound to be made or played because it doesnt know where to send it… nothing is muted everything is how it should be in cubase vst connection, device setup and mixer control application…

I´ve used the Focusright Scarlet on another mac with same cubase version and same mixer control settings and everything works, but on this mac… nope…

Any idea what my be causing this? is the driver being used elsewhere or has cubase got cancer?

You’ve installed the ASIO drivers from the manufacturer made for your interface on your system?

You selected that driver in cubase device setup - VSTaudio?

You create the bus’s you need to route audio where you want it to go or what inputs to use in VSTconnections.

So you create a bus in VSTconnections and rename it then select that bus in the track I/O.

yes to all.

But i might have managed fixed it with a temporary solution, made an aggregate device in Audio and midi setup on osx and added scarlett to it, and used that in cubase. this made it work, but i dont know how good of a solution this is, there got to be some downsides with it…