Rail passengers across Mid Wales face a further wait for the promised hourly service on the Cambrian Line through Welshpool and Newtown.
Proposals have been pushed back to 2014-15 because the single track Cambrian Line is not ready for the service.
Network Rail earlier said improvements were being made and the line could be ready by December 2013. Now the Welsh government says it expected the service to start in 2014-15 subject to funding being available.
Residents and passenger groups have long complained that a two-hour gap between trains is too long.
Proposals for an hourly service were first mooted in 2006, and the Welsh government's national transport plan scheduled it to start in 2011.
It announced a £13m project to improve the Cambrian Line in 2007 which included passing loops so trains could pass without being delayed.
But Network Rail has had problems with a European signalling system (ERTMS) on the line which became the first railway in Britain to use it in 2010.
A Network Rail spokesman said: "The Network Rail project team has worked closely with Arriva Trains Wales and the Welsh government to ensure that we deliver the objective and that it is operationally achievable.
"In hindsight, we probably would have wished to approach the project differently, as combining additional work and the new ERTMS technology at this stage has presented some difficulties.
"The main focus for Network Rail has been on installing the signalling equipment and getting this working, as without it the whole route would be affected."
A Welsh government spokesman said: "Confirming the date for the additional train services will be subject to the completion of Network Rail's further infrastructure upgrade, but we would look to the new services commencing in 2014-15 subject to availability of funding."