@mitchellb75424 The first thing I would do would be to check the voltage on the first LED. You can do this by putting the multimeter probes in the common socket (black probe) and V etc. socket (red probe). Set your multimeter to 20 VDC (V with a straight solid line and a straight dotted line) or just VDC (for an auto-ranging meter). Plug in the light strip and measure across the two solder points of the first LED that doesn't light up. What voltage do you get?