Which Look pedals do you have and what color cleats? Different color cleats have different float. You may need a different cleat and an adjustment to the cleat location (just like any clipless pedal system).
http://www.lookcycle.com/docs/techsu...eofit/?lang=en
Look has created an tool for setting up your Kéo Cleats for an optimum adjustment called the KÉO FIT. The system will help the cyclist choose the correct cleat that corresponds to their correct float based on the cyclists' pedaling anatomy.
The cleats that are available are the red cleats 9º, the grey cleats 4.5º, and the black fixed cleats. The device determines the cyclists' natural pedaling style and foot position for the most efficient pedaling.