JPA: NamedQuery of name: <query> not found

I'm using Netbeans 6.9.1 and TopLink Essentials for the JPA. I had followed the necessary steps for JPA connection.

Yet when I execute a named query in a particular entity. This e开发者_开发知识库xception always return to me

NamedQuery of name: [the query name] not found.

How is this possible and how can I resolve this?

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I had solved the problem. I can't be sure but overwriting the persistence.xml seemed to be a solution