Unable to save the node edit page

I used nodeque reference module.While saving the edit page i got the following error.

PDOException: SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '' for key 'name': INSERT INTO {nodequeue_queue} (name, title, subqueue_title, size, link, link_remove, owner, show_in_links, show_in_tab, show_in_ui, i18n, reverse, reference) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4, :db_insert_placeholder_5, :db_insert_placeholder_6, :db_insert_placeholder_7, :db_insert_placeholder_8, :db_insert_placeholder_9, :db_insert_placeholder_10, :db_insert_placeholder_11, :db_insert_placeholder_12); Array ( [:db_insert_placeholder_0] => Heritage [:db_insert_placeholder_1] => Heritage [:db_insert_placeholder_2] => Heritage [:db_insert_placeholder_3] => 0 [:db_insert_placeholder_4] => [:db_insert_placeholder_5] => [:db_insert_placeholder_6] => nodequeue [:db_insert_placeholder_7] => 1 [:db_insert_placeholder_8] => 1 [:db_insert_placeholder_9] => 1 [:db_insert_placeholder_10] => 0 [:db_insert_placeholder_11] => 1 [:db_insert_placeholder_12] => 0 ) in nodequeue_save().
Can any one help me how to resolve this issue.