ROTV II - the missing bit

Spend hours reading "hundreds" of ROTV-help-needed-posts (Joke), but got no hint: Starting from Yandros to find the next mission, I landed in the middle of it on Centauri. What did I miss? What happens, and can I go back and do the missing bit? If not, just tell me the story. Thanks.
Hy, Flatulence, some people shouldn't give away too much of the story when asking questions - spoils the fun. I hadn't been that far in the game (as you can see) and, well, thanks anyway, you spared me a lot of ...searching...

------------------
I still love Thunderstorms. Don't you?