Here are a few things to troubleshoot before calling Customer Service for your wireless invisible fence transmitter.
Make sure the transmitter is not located near any metal objects because they will interfere with the radio signal transmission making "blind spots" or interrupting the fence completely. Make sure there aren't metal sheds or other objects in the yard that are interrupting the boundary line. Take the dog's collar off and test it near and behind objects to make sure it's still receiving a signal. If the unit is plugged in but not receiving power, double-check any GFI circuits (press the reset button in the middle) and check the circuit panel to make sure there aren't tripped circuits.
If everything seems to be set up correctly, call Customer Service for further troubleshooting advice or to get a replacement unit if it's under warranty.