Auto-fish-feeder...how to keep track of time?

Ok, so it should look more like this:

if ((time - ledontime) == 648 + ledofftime) {
    ledOn();
    ledontime = time + ledofftime;
  }

In order to test the code, I tried to get the arduino to send data whenever ledOn() or ledOff() is called with Serial.print(ledontime) or (ledofftime) or with Serial.print("Hello world"), but it doesn´t seem to be working. At least nothing gets printed when I click on Serial Monitor in the Arduino IDE.