Duplicate Record Trigger

This is part of my trigger on table T1. I am trying to check if the records inserted to T1 is available in myDB.dbo.myTable or not (destination table). If it is available rollback T1. It does not do that although I insert the same records twice.
 
            -- duplicate record check
            SET @step = 'Duplicate record'
            IF EXISTS (   
                        SELECT     i.myID, i.Type
                        FROM         INSERTED i INNER JOIN
                                              myDB.dbo.myTable c ON i.myID = c.myID
                        GROUP BY i.myID, i.Type
                        HAVING      (COUNT(*) > 1) AND (i.Type = 'In')
            )
            BEGIN
                        ROLLBACK transaction
                        RAISERROR('Error: step: %s.  rollback is done.', 16, 1, @step)
                        Return
            END
           
What is problem?