Lights flicker after adding second light switch

[Josh@sip]

Adding an image of my set up

Basically this is the run across like 60-75 ft. The main line comes into a switch to control the entire line. That continues through 8 lights and then into an outlet. Originally After that outlet I had a light but I wanted to be able to control it independently from the other lights. So I added a 2nd light switch just to control the last light. The breaks out from the outlet.

So after completing the work everything works and turns on. But when I switch the 2nd light on or off, all of the subsequent lights will flash on and off quickly. I’m not really sure why and was hoping someone could help me out. Thanks

 

[tom baker]

We are unable to assist DIYers as your occupation states rental