Structure of the blueprint is problematic, need advice on debug

I want to control a sequence of point light to shine in sequence with a delay. However, the blueprint seems not working properly and the light is not shining as intended. What is the problem with the blueprint?

pl

Many. To start with, your nodes are not connected, the Index is not increasing:

image

And the Delay at the end does not delay anything since, again, it has nothing connected to it.