Hello all,
I have just started my new adventure into electronics and my first simple circuit has a problem. I have connected 4 different colored LEDS, 5mm, in parallel on a breadboard. I have made sure that all the positives and negatives are correctly connected. I have a 100 ohm, 1/4 watt resistor connected to the positive side of the LED's. I am using a 9 volt battery for power. The LED's are red, yellow, green and blue (the colored lens kind). Ok, so when I apply my power source all the LED's light up except for the blue one.
I have tried placing it in different positions relative to the others and no luck. I replace the blue LED with any other LED and they all work fine. I have also tried different blue LED's and tested them individually to ensure that they work before placing them in the circuit. I also tried using my bench top power supply, set to constant current @ 20mA and have the same results. They all light up except the blue one.
What is special about the blue LED that it will not light in the parallel circuit? I am probably missing something simple here, lol.

Thanks for any help on this.