Since your labels are Finesse and UCCE CTI Protocol, I'm assuming you are trying to connect to the Finesse Notification Service with a UCCE Finesse deloyment. As far as I remember, the XMPP connection to the Finesse notification service needs to use the agentId and not the username. So even though the library allows a connection to be made with username, it isn't going to be very helpful in the CCE deployment.
Also, is there a reason why you are trying to use CAXL vs Strophe? Strophe is the recommended library.