Other vessels cannot see me, why is this?

If the CSB 200 is not showing any Error or Timeout LED’s then it is probably transmitting your data. The static data which is sent, is in a new message Type 24, that has not been implemented in some Class A units and also in some display systems such as Chart Plotters. This means that they may not see your name, but they will see you as an MMSI number with your position, course and speed.