Correct Selection of SQL server instance db owner login name
Not sure about your specific case, but I would check to see if the login you're using is a member of the dbo role in the database you're trying to connect to.  You can query role membership using this query:

use YourDatabase;

select 
    r.name role_name,
    u.name db_login,
    u.type_desc
from (select * from sys.database_principals where type = 'R') r
    join sys.database_role_members rm on (r.principal_id = rm.role_principal_id)
    join (select * from sys.database_principals where type != 'R') u on rm.member_principal_id = u.principal_id
where r.name = 'db_owner'
order by r.principal_id,u.type_desc,u.name;


If you need to add the login to the DBO role:

Use YourDatabase;
exec sp_addrolemember 'db_owner','FOO\bar';