请教FC6 yum.conf配置问题

lee_vs

我的yum.conf配置
[main]
cachedir=/var/cache/yum
keepcache=0
debuglevel=2
logfile=/var/log/yum.log
pkgpolicy=newest
distroverpkg=redhat-release
tolerant=1
exactarch=1
obsoletes=1
gpgcheck=1
plugins=1
metadata_expire=1800

[extras]
name=Fedora Extras $releasever - $basearch
baseurl=ftp://ftp3.tsinghua.edu.cn/mirror/download.fedora.redhat.com/pub/fedora/linux/extras/6/i386
enabled=1

[updates]
name=Fedora Core $releasever - $basearch - Updates
baseurl=ftp://ftp3.tsinghua.edu.cn/mirror/download.fedora.redhat.com/pub/fedora/linux/core/updates/6/i386
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora

[core]
name=Fedora Core $releasever - $basearch
baseurl=ftp://ftp3.tsinghua.edu.cn/mirror/download.fedora.redhat.com/pub/fedora/linux/core/6/i386/os
enable=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora file:///etc/pki/rpm-gpg/RPM-GPG-KEY
# PUT YOUR REPOS HERE OR IN separate files named file.repo
# in /etc/yum.repos.d

改了yum源后好像不能用了.
[root@captain etc]# yum update gaim
Loading "installonlyn" plugin
Setting up Update Process
Setting up repositories
Reading repository metadata in from local files
Resolving Dependencies
--> Populating transaction set with selected packages. Please wait.
---> Downloading header for gaim to pack into transaction set.
ftp://ftp3.tsinghua.edu.cn/mirro ... beta6.fc6.i386.rpm: [Errno 4] IOError: [Errno ftp error] 550 Can't change directory to download.fedora.redhat.com: No such file or directory
Trying other mirror.
Error: failure: gaim-2.0.0-0.31.beta6.fc6.i386.rpm from updates: [Errno 256] No more mirrors to try.