No, that's not right. The unique assignments in a chain can be failed, and won't advance the chain until you actually successfully complete it.
There are a few missions that allow you to fail while still advancing along the assignment chain, but I don't think this is one (and they're generally noted in the wiki).
"Don't let them promote you. Don't let them transfer you. Don't let them do anything that takes you off the bridge of that ship, because while you're there... you can make a difference." - James T. Kirk
In any case, there isn't much demand on the Exchange for 'Ferasan Chag Grass'. My Main and most of my Alts have the ability to churn this stuff out, but with no demand (and profit), whats the point... http://www.stowiki.org/Ferasan_Chag_Grass
@ grouchyotaku - I'm stuck on your first link (the one require 20 Leaves).
I'm not concerned at all to sell the end product. My goal is to complete the chain. You know, when you enter sector space, open the DOff UI and on the assignment list there is this one where at the end of the title states "(3/4)". Plus, I want the assignment to be removed from the chain list.
As for the parenthesis, I've always presumed that an indicator of 1) how many assignments are in the chain and 2) how many you have completed. So, to me, I'm reading I have the final one to complete, have tried 3x and failed.
I assure you all - I have not repeated the entire chain (the cost of the leaves alone is memorable enough to make me feel confident about that).
It's starting to seem to me that it's going to be about DOff placement and luck