Just in case someone stumbles across this necrothread - I had this problem today and the root cause was that the mtu on my ldp interfaces was set too high for the link. Once I figured out what the media actually supported (/bin/ping -I eth1 -M do -s <size> <destination ip> and adjusted both my ldp link mtus and vpls link mtus (ldp mtu - 22) down, it fired right up.
HTHs someone in the future.
(edited to fix tense)