Why do French say .... " tomber dans le panneau " ?

The term "tomber dans le panneau" (fall into the trap) is used to describe a person who has fallen into a trap without realizing it. This phrase refers to the origin to the field of hunting. During the XIII century, the "panneau" (panel), from the Latin "pannellus" (piece of cloth), described a net that hunters tended to catch small game such as rabbit or hare. The animals were often deceived by this trick and found themselves prisoners. The term therefore has no connection with traffic signs (panels)  or advertising that did not exist at the time.