I became a Speed violation but i was driving 29 Knts.
were you looking at airpseed or groundpseed? they are not the same.
As @ATK already mentioned, the violation is based on ground speed, GS
Have a look at the following example:
My airspeed shows 3 knots while my ground speed shows 0. This is correct as I am parked with the brakes on. The wind has a big influence on your airspeed indication that’s where you most probably went wrong.
I would suggest to add GS on your instrument dock. As a side note, the 250 knots below 10.000 feet is based on the airspeed so don’t get confused with this.