It is possible that the timer is not sending out the voltage to the zones, but there could be an error somewhere downstream from your timer as well (water source, cut wires, etc.)
I would recommend testing the output of the timer with a volt meter (if you have one). If you cannot do that, then I would test the water source by turning the valves on manually.
You could contact our support group and they should be able to assist you with this. 1-800-488-6156