I try to rod "rear legs to back" sinks but can't capture the rod to walk downwards, it other go to the other sink. what is the secret?

what is the secret?
State the target of the short way around...
Answers:    it takes a bit of "experience" for put money on to back fixtures. i usually put a larger "head" <curve> on my snake head and progress "SLOWLY".

as you push the snake through, it will lock in on the figure fitting and go down.

if you are not comfortable beside this, you're probably better off dropping the trap arm and putting the snake down with your appendage to get it started.
Who can I complain to give or take...
One may feed to the other beforehand a trap. Take the drain apart at the trap, and go down from there.