elements with different types in a <choice>

Hi,
I'm trying to create a schema element called <bean> where the children called <field> can be of different types. I created a complexType for every field and I have a choice model that contains three elements called "field" with different types. When I try to validate the schema I get an error message saying that I am violating the unique name constraint for the model.

Does anybody know how to fix/implement this kind of structure?

Thanks


p.s. I attached the schema to this message