Something to keep in mind: you do not have a "Multiface 2 PCIe", you have a "Multiface 2" and an "HDSPe PCIe" card. You may be experiencing a problem with one or the other, probably not both.
Does the light stop flashing red at any point on the Multiface? It should turn off once the driver finds it.
Various things to try:
1. Try a different cable (it's a regular Firewire cable, but NEVER plug the Multiface directly to a Firewire or you can damage it).
2. Make sure the firmware to the card is updated to the latest version.
3. Make sure your card is not one listed in this thread: http://www.rme-audio.de/forum/viewtopic.php?id=2741
4. If you can, try another Multiface or Digiface to see if they work.
5. Try plugging the card into another PCIe slot on the same system.
6. Try providing power to the Multiface from a power adapter; almost anything around 12v will do (check the manual); however this shouldn't be necessary with PCI or PCIe
7. Try the card + Multiface on another system.
Always cut power to the system and Multiface when you rewire. Then restart. If nothing works, then contact RME support directly.
PC1 = HDSPe PCIe: DF-ADI-8 DS / HDSPe PCIe: MF2
MBP = HDSPe Expresscard: MF1