Observer Update Issues

Hi, I have a web app that is using the observer style to update information on the users screen. The issue Im having is its only updating the user that logs in first. I can see that both users container controls are being registered as observer receivers but the class thats updating them is only sending to the first observer that is in the array. The code Im using to cycle through them is.

For Each Listener As TankSensorUpdate In Listeners
Listener.Update(id,data)
Next

The information being passed is id - Integer, data - structure.

If anyone has any ideas I would greatly appreciate it.

I would do the update in a timer instead. Loop prevents UI update.

The timer worked, I put a timer in the class thats sending data to the observers which cycles through the observers in the array then sends that array number to the interface method that then pushes the data out to the user sessions. As far as the actual UI updating that was already done with a timer. Thank you for the help Michel.