FC4 Mplayer installation problem

[Ahmed Abdel-Aliem <me2resh gmail com>]

hi
i am trying to install mplayer on fc4 using yum
using this command

yum -y install mplayer mplayer-skins mplayer-fonts

but it gives me this error :

Downloading Packages:
warning: rpmts_HdrFromFdno: Header V3 DSA signature: NOKEY, key ID e42d547b
public key not available for xvidcore-1.0.3-1.2.fc4.i386.rpm

can anyone tell me what may cause this problem plz

any help would be appreciated
thanks

-- 
Ahmed Abdel-Aliem
Web Developer
www.ApexScript.com
0101108551
registered Linux user number 382789