Grant Schema privileges to User

I'm trying to grant select privileges on a Schema with no success.

I call this statement with the SYSTEM user

call _SYS_REPO.GRANT_SCHEMA_PRIVILEGE_ON_ACTIVATED_CONTENT('select','cschildxs','schildc');

and get the error:

Could not execute 'call _SYS_REPO.GRANT_SCHEMA_PRIVILEGE_ON_ACTIVATED_CONTENT('select','cschildXS','schildc')' in 0 ms 640 µs . SAP DBTech JDBC: [362]: invalid schema name: CSCHILDXS

What i've done so far:

I've created a cschildxs.hdbschema file with content:

schema_name="cschildxs";

And activated it

In the table _sys_repo.active_object i can see the Schema entry

PACKAGE_ID;OBJECT_NAME;OBJECT_TYPE_ID;VERSION_ID;ACTIVATED_AT;ACTIVATED_BY;EDIT;CDATA;BDATA;COMPRESSION_TYPE;FORMAT_VERSION;DELIVERY_UNIT;DU_VERSION;DU_VENDOR;DU_VERSION_SP;DU_VERSION_PATCH;OBJECT_STATUS

cschildXS.db;cschildxs;hdbschema;1;2013-03-08 12:00:54.091;SCHILDC;1;schema_name="cschildXS";;?;0;;;;;;;1