Problems with "_" and "?auth=digest" in RSS


I'm trying to add feed with underline sign and authorization and it last forever while FeedReader adds it.
Exactly I want to read some of my LiveJournal friends, but they have private topics, so i neet to authorize.

For example
"http://_eleara_.livejournal.com/data/rss"
or
"http://in_effect.livejournal.com/data/rss"
feeds works excellent, but when i'm trying to add this:
"http://in_effect.livejournal.com/data/rss?auth=digest"
there are some problems... (!)

And when I add normal lj-user without "_", for example
"http://antonche.livejournal.com/data/rss?auth=digest"
all is excellent and there is no problems.

P.S. I think you are working on a best rss reader that i've seen.
It is semplest in use and interface and powerful enough.