The problem I once had with this mission, not being able to collect the reward after warping out, did occur on a run where I didn't destroy the escort in the beginning of the mission.
You have to disable one ship, the one you're going to board and use for the main mission and destroy another one that has a role as an escort. You got engaged in a fight with both. At one moment the main ship was disabled and I got the message to board it. OK, I thought, forget about the other one ... wel, it didn't work for me.
The last time I ran the mission was the first time I noticed the objective to kill the escort. I wasn't sure which was the escort but assumed it was the only other ship moving around a lot. By the time I finished the Targ it was hovering around by the station with the other klingons so I shrugged and went on.
Ok, I'll give it one more go. I'll be sure to destroy the escort as well and hail starfleet while still in the mission - a habit I started last night and plan to continue.
Thanks for the help guys.
One last question... which torp? Don't recall if there was a choice of more than one or not now.