ConnectorSecurity.SecurityKey

I use the aspx connector togther with the dataprocessor.
All works fine. But if i add

ConnectorSecurity.SecurityKey = true;

nothing saves anymore.

Post:
_!nativeeditor_status updated
2_KNE_KNEID 02950483
2_KNE_Name Stadtwerke München
2_KNE_TID 2
2_LastModifiedTimestamp 2013-11-28 16:53:30
2_LastModifiedUser Z000UFF1
2_LegalFormKNEkey 100
ids 2

response goes:
XML Parsing Error: no element found Location: moz-nullprincipal:{055d5585-5b81-42b3-b7c7-20ff5fda623c} Line Number 1, Column 1:

any idears?

With best regards,
Uwe Janke

Are you loading data in the grid from the same file ?
To work correctly you need to have a loading and saving from connectors with SecurityKey set to true ( that may be two different files, but SecurityKey must be enabled in both )