Error #0009: you do not have rights to open a private chat session
Your rights group is not allowed to start private conversations one-to-one. This limitation deals with opening private conversations from any places: contact lists, search, history, conferences, notifications and announcement board.
This relates only with the start of a private dialogue on your side. If other user writes you first you will be able to reply to him.
Enable the rule "New privates opening" for a users group in the section "Rights Control" -> "Permission groups" -> "Privates" or transfer a user to a group where this rule is enabled.