DDJ-SR : Error: Not possible to connect midi device

Hi, i'm contacting you as when i connect my ddj-sr to my Mac computer, the Serato Dj software gives me the message Error: Not able to connect Midi device. I tried the MIDI Connection Troubleshooting Guide and the Midi monitor software confirms that the device is connected to my computer.
It's quiet frustrating as i upgraded to play with the controller from my old SL3 and Scratch live with cdjs and never had a single issue.

Hereby i give you the specifications of my computer and i will be awaiting for your kind help.

Mac OS 10.11
Processor 2,26 GHz Intel Core 2 Duo
Memory 2 GB 1067 MHz DDR3