Rewards are a funny thing. The right currency can motivate people to continue to act in the desired way. If the award criteria are not well understood or if the awards are perceived to be arbitrary or capricious any award program can fail.
The best currency for motivating people to contribute – especially when they may see it as risky – is not financial. People are generally well motivated by seeing their ideas taken seriously and – more importantly – tried. They are motivated by seeing that it is within their power to affect improvement. Experiencing the successful result of their ideas will perpetually drive the employee toward more ideas, which brings up the next important topic, that of Control.