Forum:Pylos Nebula and Hades Nexus don't show up (ME2)

I noticed going through the mission list for ME2 that there were some missions that I did not recognize. This shocked me as I had completed the game and I thought I had done all the possible missions. I booted up ME2 ready to do these missions only to discover a problem. These missions were located in the Pylos Nebula or Hades Nexus but checking all the possible locations on the galaxy map multiple times I did not find these locations. I play on the xbox 360 and have the crash site, Zheed, inferno armor and the 3 Dr Pepper DLCs (though I do not believe the Dr Pepper DLCs are at fault as I had already gone through all the systems I could find before completing the game or downloading the DLC). Has anyone got an idea of what might be going wrong? Do I need to talk to some obscure person to open these areas up? What are these locations near on the galaxy map to make sure I'm just not making a moronic mistake?