Jockey wheel unwinding during journey

Whilst enroute on a journey the jockey wheel unwinds and strikes the ground on our new twin axle Barcelona. Having caravaned for 27 years I am au fait with the following procedure. I wind the wheel up so that the the wheel supports are retracted into the two notches to prevent it turning. I pull up the centre column until the top of the wheel touches the underside of the A Frame and then tighten the side handle to secure the column I then turn the top handle to further tighted the wheel to the  A frame. Despite a lot of pressure the wheel unwinds inself even though the column is still locked. Never had this problem before and I don`t think it is right to have to lash the wheel up on a new caravan.