Problème "Missing Dependencies" avec YUM

Bonjour,

J'ai un problème récurrent de "Missing Dependencies" lorsque j'essaye d'installer mes rpm avec yum (je suis sous RHEL5).
Le rpm qui m'intéresse est le suivant (RRDTool), donc voici le log:

yum install rrdtool-1.3.8-1.el5.wrl.i386.rpm
Loaded plugins: security
rpmforge | 1.1 kB 00:00
Setting up Install Process
Parsing package install arguments
Examining rrdtool-1.3.8-1.el5.wrl.i386.rpm: rrdtool-1.3.8-1.wrl.i386
Marking rrdtool-1.3.8-1.el5.wrl.i386.rpm as an update to rrdtool-1.3.4-2.fc9.i386
Resolving Dependencies
--> Running transaction check
---> Package rrdtool.i386 0:1.3.8-1.wrl set to be updated
--> Processing Dependency: perl(RRDp) for package: rrdtool
--> Processing Dependency: perl(RRDs) for package: rrdtool
--> Processing Dependency: ruby for package: rrdtool
--> Running transaction check
---> Package rrdtool.i386 0:1.3.8-1.wrl set to be updated
--> Processing Dependency: ruby for package: rrdtool
---> Package perl-rrdtool.i386 0:1.3.8-2.el5.rf set to be updated
--> Finished Dependency Resolution
rrdtool-1.3.8-1.wrl.i386 from rrdtool-1.3.8-1.el5.wrl.i386.rpm has depsolving problems
--> Missing Dependency: ruby is needed by package rrdtool-1.3.8-1.wrl.i386 (rrdtool-1.3.8-1.el5.wrl.i386.rpm)
Error: Missing Dependency: ruby is needed by package rrdtool-1.3.8-1.wrl.i386 (rrdtool-1.3.8-1.el5.wrl.i386.rpm)


Le problème est que même lorsque j'essaye d'installer ruby, j'ai d'autre Missing Dependencies en chaîne.
Exemple avec le log de ruby:
yum install ruby-rpm-1.2.3-1.el5.rf.i386.rpm
Loaded plugins: security
Setting up Install Process
Parsing package install arguments
Examining ruby-rpm-1.2.3-1.el5.rf.i386.rpm: ruby-rpm-1.2.3-1.el5.rf.i386
Marking ruby-rpm-1.2.3-1.el5.rf.i386.rpm to be installed
Resolving Dependencies
--> Running transaction check
---> Package ruby-rpm.i386 0:1.2.3-1.el5.rf set to be updated
--> Processing Dependency: ruby >= 1.8.1 for package: ruby-rpm
--> Processing Dependency: libdb-4.2.so for package: ruby-rpm
--> Processing Dependency: libruby.so.1.8 for package: ruby-rpm
--> Finished Dependency Resolution
ruby-rpm-1.2.3-1.el5.rf.i386 from ruby-rpm-1.2.3-1.el5.rf.i386.rpm has depsolving problems
--> Missing Dependency: libruby.so.1.8 is needed by package ruby-rpm-1.2.3-1.el5.rf.i386 (ruby-rpm-1.2.3-1.el5.rf.i386.rpm)
ruby-rpm-1.2.3-1.el5.rf.i386 from ruby-rpm-1.2.3-1.el5.rf.i386.rpm has depsolving problems
--> Missing Dependency: libdb-4.2.so is needed by package ruby-rpm-1.2.3-1.el5.rf.i386 (ruby-rpm-1.2.3-1.el5.rf.i386.rpm)
ruby-rpm-1.2.3-1.el5.rf.i386 from ruby-rpm-1.2.3-1.el5.rf.i386.rpm has depsolving problems
--> Missing Dependency: ruby >= 1.8.1 is needed by package ruby-rpm-1.2.3-1.el5.rf.i386 (ruby-rpm-1.2.3-1.el5.rf.i386.rpm)
Error: Missing Dependency: ruby >= 1.8.1 is needed by package ruby-rpm-1.2.3-1.el5.rf.i386 (ruby-rpm-1.2.3-1.el5.rf.i386.rpm)
Error: Missing Dependency: libdb-4.2.so is needed by package ruby-rpm-1.2.3-1.el5.rf.i386 (ruby-rpm-1.2.3-1.el5.rf.i386.rpm)
Error: Missing Dependency: libruby.so.1.8 is needed by package ruby-rpm-1.2.3-1.el5.rf.i386 (ruby-rpm-1.2.3-1.el5.rf.i386.rpm)



Quelqu'un a-t-il une soilution pour outrepasser toutes ces erreurs qui m'empêchent d'installer ce dont j'ai besoin?

D'avance merci :)
Victor