Blinking leds

[Firemanpl]

Hi!
https://youtu.be/T-QoqgUnS3Y
If I touched the data pin, the blinking disappears. How to fix it.

[Andriejus]

Do you have a resistor between controller and LED?
And you have to join both ground cables (controller and LED ground should be the same:)
And its a little hard to say what could be wrong when you dont see schematics or howe everything its connected. It could be bad wires connection:)

[Firemanpl]

Ok I repaired

[biejay]

Hey, i heard different opinions about using a resistor. Is it really neceassary to have one?