ran into another problem with this mission or better said the other one you get when you hit T5 with the romulans.
it seems despite the fact that i have max reputation and the mission log clearly says i should contact d'tan i seem to be unable to start this mission while, atleast that's what i suspect, the "the Power Source" mission is on cooldown.
on a related subject...it took the system 4 days to recognice my T5 status with the omega faction so it would award me with the 9k dilithium and 500 marks.
For the last 2 missions u need to do some very similar things.
For T4 mission, u need 5 EV suits for your and your boffs, go inside and actiuvate your suit, the boffs will do it automatically if they are wearing it, and depending on your boffs they will not show it (my reman stays the same, and i have no idea why i would need to give my breen a ev suit on top of his ev suit )
Do the mission, walk down to the room and defeat the boss .... T4 mission finished....
For T5 mission , do the same ... and when u have cleared the endfight, u have a button to call in D'tan for the final movie.
It could be possible that you need to do the mission twice, once for the T4 mission, and another time for the T5 mission.
The reward for watching the T5 end movie is definatly worth it.