Duplicate entry (New) for Admin Relationship Type breaks down the page

link :
http://192.168.2.9/drupal/civicrm/admin/reltype?action=add&reset=1

Steps :
1) goto the above link and create one test relationship
2) click on the New Relation Type link
3) Enter the same relation_a_b, relation_b_a, two contacts, Info of the relation as enter for the test relation in the step (1)
4) Hit "Save"

Current Behaviour :
page breaks and shows some database error

Expected behaviour :
Error message on the page saying name or relationship already exists in the database