How do you sync cubase through Fast Track Pro

I have a Motif ES connected via 5-pin midi cable to my fast track pro, and my fast track connected to my computer, the issue I’m having is I cant get cubase to control my senquencer on my motif. If i connect my motif directly to the computer via usb I can gt it to work but then I get a humm when I connect my 1/4 to the input of the fast track.
Can anyone help or point me in the right direction.