Business View Issue

Hi everyone,

Has anyone ever got the attached error while validating a business view?

The sql is the following:

Select defect.id,
defect.name,
defect.status

From defect
Where defect.id Not In (Select Distinct (defect_link.first_endpoint_id)
  From defect_link Where defect_link.second_endpoint_type = 'TEST')
Order By defect.id

Thanks in advance.