could you help on errors on akonadi_control.error

[Sérgio Basto]

Hi, 
in /home/sergio/.local/share/akonadi/akonadi_control.error.

I got 
Executable "akonadi_nepomuk_feeder" for agent
"akonadi_nepomuk_feeder"
could not be found! 
Executable "akonadi_folderarchive_agent" for agent
"akonadi_folderarchive_agent" could not be found! 


what this means ? 

-- 
Sérgio M. B.