errorpackagegnomeusershareisnotinstalled这是什么错误？

[font='Lucida Grande', Helvetica, Arial, Verdana, 微软雅黑, sans-serif]CentOS 5.4 32位 系统 按照 http://help.aliyun.com/manual?spm=0.0.0.109.1kBRHK&helpId=129这个链接安装的。
[font='Lucida Grande', Helvetica, Arial, Verdana, 微软雅黑, sans-serif]

system will install httpd-2.2.22 and php-5.2.17
error: package httpd-2.2.3-31.el5.centos is not installed
error: package gnome-user-share is not installed
Loaded plugins: fastestmirror
Determining fastest mirrors
* base: mirrors.163.com
* extras: mirrors.163.com
* updates: mirrors.163.com
addons                                                                                                                 | 1.9 kB     00:00    
base                                                                                                                   | 1.1 kB     00:00    
extras                                                                                                                 | 1.9 kB     00:00    
extras/primary_db                                                                                                      | 173 kB     00:00    
updates                                                                                                                | 1.9 kB     00:00    
updates/primary_db                                                                                                     | 854 kB     00:00  


这两个错误什么意思？