Which McAfee Agent version are you using?
Have you check in a new agent Package recently?
Moved from Security Awareness to ePolicy Orchestrator-By Moderator
As llamamecomoquieras told, you cannot create a new McAfee Agent package until ePO builds it (after having added it to the master repository).
If this still happens some minutes after then you should delete McAfee Agnet from your master repository and check it again