Failed dependencies问题：明明已经安装，但是还提示缺少

rhel-as5下安装pidgin过程中出现的问题：
提示缺少cyrus-sasl-md5-2.1.22-6
下载安装，又提示缺少cyrus-sasl-lib-2.1.22-6
继续安装－－>成功，回头装cyrus-sasl-md5-2.1.22-6
但是还是提示缺少cyrus-sasl-lib-2.1.22-6，怎么回事？？？？

[root@localhost ~]# rpm -ivh cyrus-sasl-lib-2.1.22-6.i386.rpm
warning: cyrus-sasl-lib-2.1.22-6.i386.rpm: Header V3 DSA signature: NOKEY, key ID 4f2a6fd2
Preparing... ########################################### [100%]
file /usr/lib/libsasl2.so.2.0.22 from install of cyrus-sasl-lib-2.1.22-6 conflicts with file from package cyrus-sasl-lib-2.1.22-4
file /usr/lib/sasl2/libanonymous.la from install of cyrus-sasl-lib-2.1.22-6 conflicts with file from package cyrus-sasl-lib-2.1.22-4
file /usr/lib/sasl2/libanonymous.so.2.0.22 from install of cyrus-sasl-lib-2.1.22-6 conflicts with file from package cyrus-sasl-lib-2.1.22-4
file /usr/lib/sasl2/libsasldb.la from install of cyrus-sasl-lib-2.1.22-6 conflicts with file from package cyrus-sasl-2.1.22-4
file /usr/lib/sasl2/libsasldb.so.2.0.22 from install of cyrus-sasl-lib-2.1.22-6 conflicts with file from package cyrus-sasl-2.1.22-4
file /usr/sbin/sasldblistusers2 from install of cyrus-sasl-lib-2.1.22-6 conflicts with file from package cyrus-sasl-2.1.22-4
file /usr/sbin/saslpasswd2 from install of cyrus-sasl-lib-2.1.22-6 conflicts with file from package cyrus-sasl-2.1.22-4
[root@localhost ~]# rpm -ivh cyrus-sasl-md5-2.1.22-6.i386.rpm
warning: cyrus-sasl-md5-2.1.22-6.i386.rpm: Header V3 DSA signature: NOKEY, key ID 4f2a6fd2
error: Failed dependencies:
cyrus-sasl-lib = 2.1.22-6 is needed by cyrus-sasl-md5-2.1.22-6.i386
[root@localhost ~]#

明明已经安装了cyrus-sasl-lib = 2.1.22-6，可为何 cyrus-sasl-md5-2.1.22-6还是进行不下去呢？
郁闷中。。。