You might also have to delete txleveldb and database folders if they exist. I just had this issue this morning where it wouldn't sync, after deleting those folders it had to resync from scratch but it didn't have any issues doing so.

EDIT: Those folders are in the %APPDATA%\Lemanum folder

If that doesn't work you can try adding the nodes manually using the debug console

addnode : add

you should only have to add 2-4 for it to begin syncing, other users have reported success with doing that if the configuration file method doesn't work.