Problem Installing Simulink Real-Time Desktop

I want to run Simulink in real-time and am therefore trying to install Simulink Desktop Real-Time.

The installation is done with this command:

 sldrtkernel -install (I have also tried sldkernel -setup)

I get this answer:

 "The Simulink Desktop Real-Time kernel has been successfully installed."

I try to check if the Real-Time kernel has been installed with this command:

 "rtwho"

and get the answer:

 "Simulink Desktop Real-Time installation is not complete. Please type 'sldrtkernel -setup' to complete the installation. Type 'help sldrtkernel' for more information."

I've tried this numerous times and rebooted the computer in between but with the same result. Please help. I'm running OSX 10.10 and Matlab 2015a.