Error configuring JpaIdentityStore

[damatrix]

I have a problem using Seam's JpaIdentityStore in seam 2.1.1.GA for identity management.

I have a User class annotated as following

@Name("user")
@Entity
@Table(name="users")
public class UserImpl extends UniqueIDImpl implements User{
    private static final long serialVersionUID = -7547331292683799836L;
    @UserFirstName
    private String firstName;
    @UserLastName
    private String lastName;
    @UserPrincipal
    private String username;
    @UserPassword(hash="md5")
    private String password;
    @ManyToMany(targetEntity=RoleImpl.class)
    @JoinTable(name="user_role",joinColumns = {@JoinColumn(name = "user_id")},
                    inverseJoinColumns = {@JoinColumn(name = "role_id")})
    @UserRoles   
    private Set<Role> roles = new HashSet<Role>();

And Roles also as ff:

@Entity
@Table(name="roles")
@Name("role")
public class RoleImpl extends UniqueIDImpl implements Role{
    private static final long serialVersionUID = -7189583948477718346L;
    @RoleName
    private String rolename;  

You will notice that because I'm implementing from defined interfaces, I had to specify the targetEntity on the ManyToMany relationship and declare annotations on fields and not on properties (get/sets) as I'd have liked to do, simple because I had exceptions otherwise.

I have specified these in the components.xml file as ff

<security:jpa-identity-store user-class="com.domain.model.security.UserImpl"
        role-class="com.domain.model.security.RoleImpl"/>

Somehow, I'm unable to login, though I'm able to create user accounts which are sitting comfortably in the database. I decided to test my configuration by calling

IdentityManager.instance().createUser("michael", "essien");

And I get the following exception among other exceptions.

Caused by org.jboss.seam.security.management.IdentityManagementException with message: Error configuring JpaIdentityStore - it looks like you're using a cross-reference table, however the user property cannot be determined.

Any ideas what I'm doing wrong?