[Yum] PB with yum

[Jean-Claude Odillard]

Dear all,

I am a new user of yum and yumex. At this time , I don't know what 
appends. When I lauched some traitements. all is good unless some 
dependancy. But when I pass this gap I sawin the terminal windows. The 
following message " look after the key". After that a error wondows tell 
me :
/nError checking package signatures:
yum.Errors.YumBaseError

What can I do to go away from this situation?
Thak you at all
Bst Rgs