What client is that? Diablo II or WarCraft II, I'm guessing.
The issue is that CheckRevision version two used Int64 instead of Int32, effectively doing nothing more than cause some bots to crash for a while. iago fixed this, but I forgot to patch my copy of JavaOp2 up with this before applying the BNLS fixes.
I'm busy right now but when I get a chance I'll fix it and upload a BNetLogin.jar hotfix for you.
I'm curious why you're getting the BNLS error, however. Is it down right now?