Selenium test (python) on slider with angular js based UI

I ma trying to set a UI slider (Label=ON/OFF, Slider, Apply button) based on Angular JS with selenium.

(see the code in comments)

Tried next python code: (instead of send_keys I used java-script; since send_keys is not working visualy)

(see the code in comments)

Visually the python code perform well the job: moving my slider from left to right and the click on the element (with offset on the right side). But the label 'strong' does not change to ON and also (verified with Firebug->Net) after I press Apply the value sent to back-end is OFF (and not ON as expected). Please let me know about any idea on how to fix this issue? Thanks