PowerPivot not detecting foreign key relationships from SQL Server 2005

Question

I am importing data from tables in SQL Server 2005 to a PowerPivot workbook. They are production databases, so I only have datareader access. If I try to select related tables during the import, it does not find any, nor does it create any relationships from the foreign keys that exist in the database. If I try to import data from a development machine (that I am db_owner on, and also happens to be a SQL 2012 instance) then it all works fine.

I have tried the same thing from a Tabular model project, with exactly the same outcome. Does anyone know if this is a permissions thing, or related to importing data from SQL Server 2005.

Thanks in advance

Paul