unresolved class in security policy

Hello all there,

I'm configuring a policy file in Tomcat 5.0.18 but I have some issues.
One of the grants I'm specifying is:

grant principal es.bfc.security.auth.BancovalUserPrincipal "eduardo.yanez" &
#123;
permission yy.xxx.security.auth.ExecutionPermission "Multi-idiomaLogin2";
};

where yy.xxx.security.auth.ExecutionPermission is a subclass of java.securit
y.BasicPermission.
When I start Tomcat (start -security) with -Djava.security.debug=all option,
 Tomcat says this:

policy: Adding policy entry:
policy:   signedBy null
policy:   codeBase null
policy:   yy.xxx.security.auth.BancovalUserPrincipal/eduardo.yanez
policy:   (unresolved es.bfc.security.auth.ExecutionPermission Multi-idiomaL
ogin2 null)

What must I do in order to Tomcat could resolve my class?