Hmmm, Ok, that means it can't see the drive is in there. That could be hardware.
Did you pop out the old card or pull it out? It should pop out, (this is similar to how my camera takes it's battery for example, push in and it pops out) or did you pull it out? I kinda didn't realize it'd pop in/out when I first did this. Power down and try poping it out and then putting it back in. Just trying to make sure the new card has a proper connection to the phone so that the phone can see it.
Ok, I'm not at all familiar with rooted/custom ROMs so this may be way beyond my pay grade, might have to wait for someone else to come along who knows more.