LED strip doesnt turn on when connected to external power source

my wiring is: led + to supply + pi and led gnd to supply gnd pi gpio18 to led data see attached picture. It does turn on if i connect the led power to the pi, but its not enough power

how is that led data wire connected? provide your code.

im using https://github.com/onlaj/Piano-LED-Visualizer

the data wire from the leds is connected to the gpio18 pin on the pi, and the code is not the issue here, it works when i give it power from the pi

only stops working when i give it external power