Sorry mate - please re-read your initial post.
From that we don't know what exactly you're doing.
We don't get to know what privileges you assigned to which user.
And you didn't tell us, what you have tried to solve the issue or what you learned during your search.
Basically it looks exactly like one of the many "I let others do my search work"-posts.
Just as any other reasonable developer forum, in SCN we expect users to not just cry for help but to show us what they have already done and where they got stuck.
Anyhow - most likely _SYS_REPO lacks INSERT privilege WITH ADMIN OPTION on the table.
Cheers,
Lars
BTW: there are many SAP internal communities that are not as public as SCN...