2 lights on same circuit controlled by 2 switches
I have a 3 switch plate on my wall. One switch is for an indoor light switch ( 3 wire, as there are 2 on the same line). The other 2 switches are two separate outdoor light fixtures. I am replacing 2 outdoor (motion sensor) light fixtures that are controlled by 2 switches. Originally, the two lights were connected together by a very thin, 3-connector(?) flat cable which is also being replaced. The first light when replaced by itself worked, but when I turned both switches on it now stops working. I am still trying to get the first one (closer to the switch) to work.
The old flat cable did not have colored wires, didnot help me with how the two lights were connected, except the middle wire was wired around the cable itself, or not used.
How do I make sure I have them connected right and both to operate?