Why does the light go out...

[Pamela Galli]

....when there are two lamps, if I turn on a second lamp, the first one goes out, or appears to?

 

And what can I do about it?

[Innula Zenovka]

Until recently, viewers could only show light from six light sources (plus sun and moon).   Since Viewer 2.7.1, you've been able to see light from an infinite number of local light sources, if you've got lighting and shadows enabled. But not everyone has their graphics set this way, nor even can do in some cases.

So, the practical answer, I guess, is to rearrange the other local light sources.   Don't forget facelights count and that SL light can go through walls.    In the old, old forums, there's an interesting discussion and a very useful post by Kitty Barnett about this -- it's complicated.

[WhiteStar Magic]

I assume that you are talking about two or more light fixtures with scripts.  It's quite likely that the scripts in the lights are scripted for touches and when touched they send out "i was touched" message on a designated chat channel.  Other fixtures with the same script would "hear" the message and act accordingly. 

In simple terms  Listen for msg, when hear msg,  If light = off then turn on, IF light on then turn off.

The solution is to either modify scripts to not chat & listen and only respond to touch, or modify the script to listen to different channels (this could / would break home control systems etc....)  This of course provided that you an modify the object & scripts contained. 

[Alicia Sautereau]

Sounds like a very badly scripted light controller

[Innula Zenovka]

Yeah, but given that the OP has been running a large and successful furniture store in SL for as long as I can remember, I'm thinking she'd have noticed it before if her light scripts were that bad, or her customers would (and I've not seen any problems with lights in stuff I've bought from her).

[Alicia Sautereau]

*oops* then it must be an older client