6 Answers

A bad bulb or a break in the wire.

Most common cause is a loose bulb.It only takes one bulb to be defective & the whole string goes out. Unless you have Gremlins in the system.Then you need a new string of lights.:)

"It's better to burn out than it is to rust"  Jerry Garcia 

Made in China.

Where the bulb screws in there must be contact on the bottom and side for the bulb to work. Look inside plug and see if there is a metal bar on side of the plug. It could not be making contact with side of bulb. Just found that out today.

Poor manufacturing, along with the fact they are usually stored  abt 11 months out of the year in the extremely hot attic, damp basement or some out building exposed to both extremes. They do not hold up.