Can't connect more than 2 Joysticks

[vsilvalopes]

Hi ! I'm running sixad on a Ubuntu 16.04 machine, and it works flawlessly, when pairing controllers.

My only issue is when I try to pair more than 2 joysticks. The third and the fourth one, simply won't connect. The LED lights just blink, and the subsequent joysticks won't connect. If I power off one joystick, the other pair successfully.

I'm using sixad based on the Retropie script.

Thanks in advance!