Hi Melo,
That error message would occur if you try to turn anything on when you have the GUI set to a device that is not at present plugged in and powered on.
Are you able to turn on/off LEDs and stirring for the reactor, but NOT pumps when they are plugged in to that reactor?
Which port in the control computer is your reactor connected to? Is this the same port you have selected in the M0-M7 buttons in the GUI? If the answer is not M0 for both try setting both to M0.
Do all your reactors have pumps plugged in to them?
.
