Can't save gnus messages

[Haines Brown]

Setting up a new and updated installation of emacs, gnus, etc., on linux
debian squeeze. 

Usually I have been saving messages in gnus newsgroups by doing: C-o, and
offer a path and name for the saved file. For example, I might want to
rename a message file as "file-discussion" in my ~/sort/ directory.

However, when I try to do that, it fails: "permission denied". The
~/sort directory belongs to me and has the permission: drwxr-xr-x. I
have no trouble writing to this directory from a command line.

Haines Brown