SQL Server 2008 – How to Grant Permission

I've got a database-role, -login and user

CREATE LOGIN dummyLogIn WITH PASSWORD = 'dummyPassword', CHECK_POLICY = OFF;
CREATE USER dummyUser FOR LOGIN dummyLogIn;
CREATE ROLE "dummyRole";

with user related to the role:

EXECUTE sp_addrolemember N'dummyRole', N'dummyUser';

everything fine to this point.

now i grant select WITH GRANT OPTION to the group for a specified table:

GRANT SELECT ON "dbo"."mytable" TO dummyRole WITH GRANT OPTION;

still everything is OK. if i lookup preferences of role in ssms, i see "dummyUser" is a member of this role and the role hast SELECT permission on myTable, including the permission to grant select ( both checkboxes are tagged in preferences-window )

if i try to grant select permission to another group, which is definitely existing i get an errormessage ( no 15151 ): search for object "myTable" not possible, because object doesn't exist or necessary permissions don't exist. ( errormessage was in German 😉 ).

I can easily do a select on the mentioned table – so i assume, the object DOES exist.
and i should be able to grant select permission to another group, in my opinion.

@appended:

query which throws the error:

GRANT SELECT ON "dbo"."mytable" TO childDummyRole ( logged in as user dummyUser )

childDummyRole and referring objects have been created in the same way as the above mentioned objects:

CREATE LOGIN childDummyLogIn WITH PASSWORD = 'childDummyPassword', CHECK_POLICY = OFF;
CREATE USER childDummyUser FOR LOGIN childDummyLogIn;
CREATE ROLE "childDummyRole";

with user related to the role:

EXECUTE sp_addrolemember N'childDummyRole', N'childDummyUser';