The Sector was operated by a trainee under the supervision of a training officer. The trainee was nearing the final stages of both sector training and the end of training to obtain an air traffic control licence. Enroute after passing Oodnadatta at Flight Level 260 the crew requested and were approved for climb to Flight Level 280. This change of level was not passed on to Darwin. No loss of separation occurred. The attention of the controllers on the Melbourne sector was diverted when they received co-ordination on an aircraft for which no details were held. Traffic conditions were busy. Significant Factors The following factors were considered relevant to the development of the incident: 1. Controller attention diverted by another task. 2. Both the trainee and the supervising controller overlooked the need for co-ordination with Darwin.