I had the same issue for quite awhile. I finally got it resolved by using the following format:
http://mysiteaddress/feed
Any variation on that gave me that same “URL is inaccessible” error you were seeing. I used to be able to use the “only show posts tagged with linkedin” feature, but it no longer appears to work.
Ah, the slow auto-update system. Thanks for letting me know – I’ll check it out. I upped my vote to 5 stars, because with this fix, it’s a brilliant plugin! 🙂
