A simulation will not run if it has no ground. When you probe voltages in a simulation, all voltages are measured with respect to ground. Therefore before it can show you any meaningful voltage values, the simulator needs to know were that ground is in your circuit. So, when you create an active simulation schematic (i.e. a schematic that you wish to run in simulation) then there must be at least one point or node in the circuit that is at ground (0 or 0V). To establish a ground node, you must place one of the two available ground symbols from the Wiring Tools palette onto one of the wires in your circuit diagram.  For examples, please see: <https://easyeda.com/file_view_All-simulation-schematics-MUST-have-a-ground-01_y20YWvRPp.htm> and: <https://easyeda.com/file_view_All-simulation-schematics-MUST-have-a-ground-02_4WUSQNLJ5.htm> in: <https://easyeda.com/project_view_Spice-tutorials_AysKEWevN.htm>