Human Resources Access Group

Hi OpenERP Community

I would like to ask, which access group suitable for an employee that only allow to access human resources menu?

I set
- Useability / Extended View
- Employee
- Human Resources / User

But if i login using this user, and when i go to Human Resources -> Holidays -> Allocation Requests
i couldn't confirm this request it shows this error:
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Operation prohibited by access rules, or performed on an already deleted document (Operation: create, Document type: Leave).
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So how to set the access group so i can allow the employee to confirm the allocation request but when in the approval state, user don't have right to approve it unless it is manager.
Thanks

John