As with any device that receives information, it can take time for all messages to be picked up. At peak times there can be as many as 300 messages being transmitted, and as such your device will systematically register the information it receives as it processes the data.
In addition, please check that your antenna is connected and properly positioned. Confirm that you are in a broadcast area. If you are in a poor reception area (many things can affect FM reception such as s tall buildings and the landscape), try again in a different location.