BlinkStick Squares cannot be turned off


Hi, I ordered 12 BlinkStick Squares and Enclosures which came assembled as 12 lamps. I plugged them into my computer in order to do my experiment. Basically, some or all of the 12 lamps will be turned on depending on a participant’s choice. So before the experiment, I pasted the following lines into the debug window to test whether all the lamps are working.

from blinkstick import blinkstick
for bstick in blinkstick.find_all():

And it turns out just fine. That is, every one of the lamps can be turned on properly. However, when I try to turn off the lamps with the following commands, problem arises.

from blinkstick import blinkstick
for bstick in blinkstick.find_all():

Sometimes i can turn all the lamps off at once, but other times there can be certain lamps (one to three lamps approximately) that cannot be turned off, then I have to try the turn-off command lines again and again in order to turn all of them off (sometimes, there is one lamp that stays on no matter how many times I try).

I don’t think the problem lies in the lamps because the lamps that cannot be turned off do not seem to be the same bunch of lamps each time I experiment with my program. I have tried to change a few ones and the problem still exists.
And when I run my experiment, the problem remains. That is, some lamps that have been turned on previously cannot be turned off afterwards.

I wonder what causes the problem and could you please offer me some suggestions as to how to fix this bug? I’d really appreciate your help!

p.s. The following information may be helpful for you to judge where the problem can possibly lie:
My computer system is Windows7 Home version (64 bit). I installed Python 2.7.9 and OpenSesame3.2.5-py2.7 to run the experiment.