You're on the right track with the order of pressing the buttons. The instructions state to press the first button 0.5 sec prior to the second button. It takes several tries but eventually it will illuminate the LED and then send signal and then start car. I have tried every conceivable way of pressing the two buttons...same time...0.5 sec, 1.0 sec...etc.
It has seemed to have gotten worse since the the first day of install. For the first day and a 1/2 or so, I do not recall having this problem. Also, one of the remotes is worse than the other. For example, the remote that is on my wife's set of keys only took me pressing both buttons a three x's to activate RS. Still waiting for a response from Carvox and my seller...not holding my breath.