Beaglebone PWM problem

Hello everyone:
I'm just tried servo motor in beaglebone black, but look like it's doesn't working.
My debian kernel version is: 4.1.6-ti-r17
PWM: P8_19

I have referenced from here(am33xx_pwm-00A0.dts, BB-PWM2-00A0.dts):
https://github.com/beagleboard/bb.org-overlays

and Adafruit_BBIO simple code(last version):
https://learn.adafruit.com/controlling-a-servo-with-a-beaglebone-black/the-python-console

but it always told me:
Traceback (most recent call last):
  File "test.py", line 6, in <module>
    PWM.start("P8_19", 50, 1000, 1)
IOError: [Errno 2] No such file or directory: '/slots'

How can I check PWM is ready? I have checked it load in my bone_capemgr.
root@beaglebone:~# cat /sys/devices/platform/bone_capemgr/slots
 0: PF----  -1
 1: PF----  -1
 2: PF----  -1
 3: PF----  -1
 4: P-O-L-   0 Override Board Name,00A0,Override Manuf,BB-SPI0-01
 5: P-O-L-   1 Override Board Name,00A0,Override Manuf,am33xx_pwm
 6: P-O-L-   2 Override Board Name,00A0,Override Manuf,BB-PWM2
 
Have any one can give me suggestion? 

Thanks,
Cloud

Please try the most recent version of Adafruit_BBIO from GitHub:
https://github.com/adafruit/adafruit-beaglebone-io-python

Matthew West did an awesome job adding PWM support for Linux 4.1+ kernels:
https://github.com/adafruit/adafruit-beaglebone-io-python/pull/108

It was merged 9 days ago by ladyada.

cheers,
drew