when set two flows with different periods,cant get the reult,which log the "The specified constraints MIGHT NOT be satisfiable"

[Glory-Yin]

here is the test code,which overwrites the SmallScenario.java
the network is 4 devices and 6 switches and 2 flows,when flow1 send at 2ms, flow2 send at 2ms，the result is ok
when flow1 send at 2ms, flow2 send at 3ms，the result is NOT be satisfiable.
but i dont know why,becasue the z3 just give the final result,but which constraint is unknown.

package com.tsnsched.generated_scenarios;
import java.util.;
import java.io.;
import com.tsnsched.core.nodes.;
import com.tsnsched.core.components.Cycle;
import com.tsnsched.core.components.Flow;
import com.tsnsched.core.components.PathNode;
import com.tsnsched.core.network.;
import com.tsnsched.core.schedule_generator.*;
import com.tsnsched.core.components.Port;

public class SmallScenario {
public void runTestCase(){

	/*
	 * GENERATING DEVICES
	 */
	Device ccu = new Device(1000, 0, 1000, 1500);
	ccu.setName("ccu");
	
	Device ccu2 = new Device(1000, 0, 1000, 1500);
	ccu2.setName("ccu2");
	
	Device tcu = new Device(1000, 0, 1000, 1500);
	tcu.setName("tcu");
	
	Device bcu = new Device(1000, 0, 1000, 1500);
	bcu.setName("bcu");

	/*
	 * GENERATING SWITCHES
	 */
	TSNSwitch switch0 = new TSNSwitch("switch0", 100, 1, 125, 1, 400, 3000);
	TSNSwitch switch1 = new TSNSwitch("switch1", 100, 1, 125, 1, 400, 3000);
	TSNSwitch switch2 = new TSNSwitch("switch2", 100, 1, 125, 1, 400, 3000);
	TSNSwitch switch3 = new TSNSwitch("switch3", 100, 1, 125, 1, 400, 3000);
	TSNSwitch switch4 = new TSNSwitch("switch4", 100, 1, 125, 1, 400, 3000);
	TSNSwitch switch5 = new TSNSwitch("switch5", 100, 1, 125, 1, 400, 3000);
	
	/*
	 * GENERATING SWITCH CONNECTION PORTS
	 */
	Cycle cycle0 = new Cycle(50);
	Port port0 = switch0.createPort(switch1, cycle0);//switch0 use x11 to connect switch1 
	port0.setPortNum(11);
	port0.setName(port0.getName()+ "Port"+ "11");
	
	Cycle cycle1 = new Cycle(50);
	Port port1 = switch1.createPort(switch0, cycle1);
	port1.setPortNum(4);
	port1.setName(port1.getName()+ "Port"+ "4");
	

	Cycle cycle2 = new Cycle(50);
	Port port2 = switch1.createPort(switch2, cycle2);	
	port2.setPortNum(1);
	port2.setName(port2.getName()+ "Port"+ "1");
	
	Cycle cycle3 = new Cycle(50);
	Port port3 = switch2.createPort(switch1, cycle3);
	port3.setPortNum(2);
	port3.setName(port3.getName()+ "Port"+ "2");
	
	Cycle cycle4 = new Cycle(50);
	Port port4 = switch2.createPort(switch3, cycle4);
	port4.setPortNum(1);
	port4.setName(port4.getName()+ "Port"+ "1");
	
	Cycle cycle5 = new Cycle(50);
	Port port5 = switch3.createPort(switch2, cycle5);
	port5.setPortNum(2);
	port5.setName(port5.getName()+ "Port"+ "2");
	
	Cycle cycle6 = new Cycle(50);
	Port port6 = switch3.createPort(switch4, cycle6);
	port6.setPortNum(1);
	port6.setName(port6.getName()+ "Port"+ "1");
	
	Cycle cycle7 = new Cycle(50);
	Port port7 = switch4.createPort(switch3, cycle7);
	port7.setPortNum(2);
	port7.setName(port7.getName()+ "Port"+ "2");
	
	Cycle cycle8 = new Cycle(50);
	Port port8 = switch4.createPort(switch5, cycle8);
	port8.setPortNum(4);
	port8.setName(port8.getName()+ "Port"+ "4");
	
	Cycle cycle9 = new Cycle(50);
	Port port9 = switch5.createPort(switch4, cycle9);	
	port9.setPortNum(11);
	port9.setName(port9.getName()+ "Port"+ "11");


	
	
	/*
	 * LINKING SWITCHES TO DEVICES
	 */
	Cycle cycle10 = new Cycle(50);
	Port port10 = switch0.createPort(ccu, cycle10);
	port10.setPortNum(9);
	port10.setName(port10.getName()+ "Port"+ "9");
	
	Cycle cycle11 = new Cycle(50);
	Port port11 = switch5.createPort(tcu, cycle11);
	port11.setPortNum(9);
	port11.setName(port11.getName()+ "Port"+ "9");
	
	Cycle cycle12 = new Cycle(50);
	Port port12 = switch2.createPort(ccu2, cycle12);
	port12.setPortNum(9);
	port12.setName(port12.getName()+ "Port"+ "9");
	
	
	Cycle cycle13 = new Cycle(50);
	Port port13 = switch4.createPort(bcu, cycle13);
	port13.setPortNum(9);
	port13.setName(port13.getName()+ "Port"+ "9");
	
	/*
	 * GENERATING FLOWS
	 */
	LinkedList<PathNode> nodeList;

	Flow flow1 = new Flow(1,0,2000);
	//Flow flow1 = new Flow(Flow.UNICAST);
	flow1.setStartDevice(ccu);
	flow1.addToPath(ccu,switch0);
	flow1.addToPath(switch0,switch1);
	flow1.addToPath(switch1,switch2);
	flow1.addToPath(switch2,ccu2);
	flow1.addToPath(switch2,switch3);
	flow1.addToPath(switch3,switch4);
	flow1.addToPath(switch4,bcu);
	flow1.addToPath(switch4,switch5);
	flow1.addToPath(switch5,tcu);
	
	flow1.setPriorityValue(5);
	flow1.setFixedPriority(true);
	//flow1.setPacketSize(1500);
	//flow1.setFlowMaximumLatency(1000);
	flow1.setFlowSendingPeriodicity(2000);
	
	
	Flow flow2 = new Flow(1,0,2000);
	//Flow flow2 = new Flow(Flow.UNICAST);
	flow2.setStartDevice(ccu);
	flow2.addToPath(ccu,switch0);
	flow2.addToPath(switch0,switch1);
	flow2.addToPath(switch1,switch2);
	flow2.addToPath(switch2,ccu2);
	flow2.addToPath(switch2,switch3);
	flow2.addToPath(switch3,switch4);
	flow2.addToPath(switch4,bcu);
	flow2.addToPath(switch4,switch5);
	flow2.addToPath(switch5,tcu);
	flow2.setPriorityValue(5);
	flow2.setFixedPriority(true);	
	//flow2.setPacketSize(1500);
	flow2.setFlowSendingPeriodicity(2000);//when set it to 3ms，the result is not satisfied
	//flow2.setFlowMaximumLatency(1000);
	
	/*
	 * GENERATING THE NETWORK
	 */
	Network net = new Network(25);
	net.addDevice(ccu);
	net.addDevice(ccu2);
	net.addDevice(tcu);
	net.addDevice(bcu);

	net.addSwitch(switch0);
	net.addSwitch(switch1);
	net.addSwitch(switch2);
	net.addSwitch(switch3);
	net.addSwitch(switch4);
	net.addSwitch(switch5);
	
	net.addFlow(flow1);
	net.addFlow(flow2);
	
	ScheduleGenerator scheduleGenerator = new ScheduleGenerator(false);
	scheduleGenerator.generateSchedule(net);


}

}