warning unknown sobre sesiones

[miguelcubas]

Hola a todos.

Tengo un problemilla en el cual al programar una variable de sesion, se hace sin
problemas. Pero al intentar hacer un echo me surge un error que dice:

Warning: Unknown: Your script possibly relies on a session side-effect which existed until PHP 4.2.3. Please be advised that the session extension does not consider global variables as a source of data, unless register_globals is enabled. You can disable this functionality and this warning by setting session.bug_compat_42 or session.bug_compat_warn to off, respectively. in Unknown on line 0


Cual es el motivo de esta alerta.???

Gracias.