Can you give us the description, or a supplier and part number for the led strip.
It appears to have only +5, R, G, B without the usual ground connection.
Is there a GND connection on the back of the strip?
If not, it may be that the R, G, and or B need to be connected to ground (supply negative) to make those LEDs light.
I have not personally used this sort of strip.
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Is it described as "common anode" anywhere?