 From 29 December 2009, Myki became valid for travel on all metropolitan train services (but not trams and buses), in a politically driven move to meet a promise by Transport Minister Lynne Kosky and Premier John Brumby to have the system working by the end of 2009.The limited rollout was said to be due to reliability problems with the equipment on Melbourne's trams and buses.It was reported that the use of Myki on trams was being halted by signal drop-outs, related to the heavy steel construction of the trams, which was hindering the wireless communications required; and the overhead electrical systems may possibly have had a detrimental effect on performance.