AddStreamEntries failed (Access was attempted on a null reference variable)

Hi,

I made a short simple code to call this method (AddStreamEntries ) in a test service and get this error when calling it:

ErrorCode(ca207d29-837d-4110-b096-a43f1299cee8), Cause(null), Reason(Access was attempted on a null reference variable.), Possible Resolutions(Remove the reference to the null variable within your extension code.)

var stream = Things["TestCBStream"];
var values = stream.CreateValues();
values.AddRow({name: "toto"});
stream.AddStreamEntries({values: values});

TestCBStream is just a simple Stream with a testShape which has only one field "name".

The output of the execute method (in the Composer, logged in as Administrator) says:

"Error executing service AddPermissionToSuperUser. Message :: Wrapped java.lang.NullPointerException - See Script Error Log for more details."

I tried add permissions to SuperUser everywhere, but it changed nothing. I read the article