Fade problem on digital sandbox

I have exactly this problem with my Sandbox:

led 5, 6 works fine but not 4,7,8

The LEDs are working if analog output is over128 (256/2) but it is no different between 128 and 256 the LEDs light with same intensity.

What could be wrong?

PWM is only available on PWM pins (3, 5, 6,9, 10 and 11). On other pins, since there’s no hardware PWM, analogWrite() just outputs LOW for values under 128, HIGH for values above 128.

Than you!