How can I fix my gearbox on a 2004 Ford Transit Van?

My van won't select any gear while the vehicle is running, but will select while it's off and the ignition on? It's a manual box with push button R N D on the dash. Iv'e tried unplugging the wiring connectors and cleaned, but still nothing. You can hear it trying to, but the little orange lights above the buttons just flash. Help would be appreciated. Cheers.