Replying to my self.
I was using the modeshape package for JBoss AS and it seems that the admin user defined does not have admin role.
To change it, simply edit the file $JBOSS_AS_HOME/<profile>/conf/props/modeshape-roles.properties and append the admin role to the admin user.
another related question: The documentation deals with setting permission on repository or on a workspace, using the following Modeshape custom syntax:
from what I experiencied here is the working syntax, assuming the role is user1:
Where store is the repositorySourceName (probably the store name). Putting the repository name, in my case, I use the defaut repository named "repository" does not seem to work.
Is it the expected behavior or maybe I get something wrong ?