Send proper error message.
Send proper error message.

svn path=/trunk/; revision=8498

matzipan/evolution-data-server,gcampax/evolution-data-server,matzipan/evolution-data-server,gcampax/evolution-data-server,matzipan/evolution-data-server,Distrotech/evolution-data-server,Distrotech/evolution-data-server,tintou/evolution-data-server,matzipan/evolution-data-server,Distrotech/evolution-data-server,gcampax/evolution-data-server,tintou/evolution-data-server,Distrotech/evolution-data-server,Distrotech/evolution-data-server,gcampax/evolution-data-server,matzipan/evolution-data-server,tintou/evolution-data-server,tintou/evolution-data-server