It's due to the DDoS attacks on LJ. Once you get the error in your inbox, you'll need to go edit the entry that failed to crosspost, recheck the crosspost ticky box, and save the entry. That will tell DW to try again and hopefully, DW will be able to connect in round two. Until the DDoS attacks stop, there will be a much higher risk of failure in the crossposting feature.
no subject