key problem in repository

[adel.essafi at laposte.net]

Dear all
I have succeded to install a local repository.
Now, there is a problem with the key. When trying to lunch the installation
from a local PC, I got this. Could you help please.
Thanks

[root at wn1 adel]# yum -y install thunderbird
Loading "installonlyn" plugin
Setting up Install Process
Setting up repositories
base                                                                 [1/2]
base                      100% |=========================|  951 B    00:00
updates-released                                                     [2/2]
updates-released          100% |=========================| 1.2 kB    00:00
Reading repository metadata in from local files
Parsing package install arguments
Resolving Dependencies
--> Populating transaction set with selected packages. Please wait.
---> Package thunderbird.i386 0:1.5.0.7-1.fc5 set to be updated
--> Running transaction check

Dependencies Resolved

============================================================================
=
 Package                 Arch       Version          Repository        Size
============================================================================
=
Installing:
 thunderbird             i386       1.5.0.7-1.fc5    updates-released   21 M

Transaction Summary
============================================================================
=
Install      1 Package(s)
Update       0 Package(s)
Remove       0 Package(s)
Total download size: 21 M
Downloading Packages:
warning: rpmts_HdrFromFdno: Header V3 DSA signature: NOKEY, key ID 4f2a6fd2


Public key for thunderbird-1.5.0.7-1.fc5.i386.rpm is not installed


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