NULL_KEY in llSensor() ?

Hello,
Does anyone know why i detect a NULL_KEY when i search agents with llSensor()?

i use :
llSensor("", NULL_KEY, AGENT, sensorrange, TWO_PI);

and it returns, among the avatars, also a null key.

any ideas would be very welcome.

Cheers

If it's only occasionally it could be a Linden or a LL employee, I seem to remember they used to return null keys, ( or not show up at all ).

If it does it all the time, is the null always in the same place, ie at the end of the list ?
Make sure you're not reading too many items back from the list

Also PI will give you a full directional search, 2 X PI maybe confusing it ? ( i expect it's clamped though ). see the diagrams here .. http://secondlife.com/badgeo/wakka.php?wakka=llSensor

I had something similar happen when I removed a sensor set up by llSensorRepeat before processing the list....

The following code returned NULL_KEY for every entry

sensor(integer total_number) 
{
      llSensorRemove();
      for(i = 0;i < total_number;i++)
      {
            key id = llDetectedKey(i);
            string name = llKey2Name(id);
            ......
       }
}

Where as this version worked

sensor(integer total_number) 
{
      for(i = 0;i < total_number;i++)
      {
            key id = llDetectedKey(i);
            string name = llKey2Name(id);
            ......
       }
      llSensorRemove();
}

Lindens can choose if they show up in a Sensor or not, and if not they simply don't show up. I make a HUD radar for sale, and one time was talking to a Linden and had them show up on my radar, then he seemed to do something in the menu and suddenly wasn't on the radar anymore

As for the NULL_KEY thing, make sure you're not checking past the total_number variable, and as Newgate said you're not removing a SensorRepeat during the checks. Can you post your code, or snippets, to help track it down if you can't figure it out?