I read through some LED threads, and I think I may have run into a problem that they have as well...
I wanted to change red and green lights on my sound controller to blue and white.
I matched up the right size, and ordered them. I figured that an LED was an LED, but I was wrong. I later read that blue and white LED's usually require 4v m versus the 1.3-2.0. Now I have 7 superbright blue and 7 superbright white LEDs.
EDIT: I tested it with a 9v battery, and they work... 3 work at once. I'll try 4 later, unless the number doesn't matter.
I have to test the LED's as well, so I'm going to find a battery somewhere... I don't have any 9v batteries, so I'm going to try to find a AA.