Errorcode 41 and 53 trying to backup ESXi virtual machines

Hello all,
we are trying to backup virtual machines from a ESXi Host using virtual appliance as agent but it fails.
We get this error message:
ProtectCommand: Ausführen des Befehls fehlgeschlagen.
Zusätzliche Info:
--------------------
Fehlercode: 41
Module: 307
LineInfo: e6792a5ee190dd9e
Felder: $module : agent_protection_addon_glx_pic
Nachricht: ProtectCommand: Ausführen des Befehls fehlgeschlagen.
--------------------
Fehlercode: 53
Module: 309
LineInfo: 2e7e9e174f1fb746
Felder: $module : agent_protection_addon_glx_pic
Nachricht: TOL-Ergebnis 'Cumulative Completion'.
--------------------

Our EXSi Host 4.1 was the free version, a few day ago we purchased vSphere Essential and applied successfully the new license key.
It would be great, if somebody could help.
Thank you.

Kind regards,
Roland