Originally Posted by Davet

That type of brake lever wasn't designed to be used as a 'stand-alone' brake lever, rather as an in-line brake lever. It pushes against the brake housing while the cable remains stationary to actuate the brakes. There has to be a relatively large amount of housing movement in order for this style of lever to work.

I'd suggest using the standard type of brake levers that suit the handlebar and brakes system that you're using.