Part Of My Strip Light Does Not Work?

This phenomenon is most commonly caused by mechanical overstress on the product's circuit board that has caused a fracture of one of the solder joints, or of the circuit board itself. This can cause part of the lighting circuit to fail to emit light or will do so only when the strip is bent in a certain way. 

In these instances, the reliability of the product is highly diminished and should be replaced to ensure correct product operation on a long-term basis.