@User, when you add a .probe or a .save (i think these are synonims)ngspice does no more save all voltages, instead only the specified voltages are saved (unless you also have a .probe all). If the .probe/.save specifies non existent nodes or there is some syntax problem no voltages are saved at all. In this case ngspice omits the analysis. Again, if you can send the netlist, i can do some tests here.