diff --git a/Bench4Q-Master/src/main/java/org/bench4q/master/domain/entity/TestPlan.java b/Bench4Q-Master/src/main/java/org/bench4q/master/domain/entity/TestPlan.java
index 9ff78811..cebcae9a 100644
--- a/Bench4Q-Master/src/main/java/org/bench4q/master/domain/entity/TestPlan.java
+++ b/Bench4Q-Master/src/main/java/org/bench4q/master/domain/entity/TestPlan.java
@@ -263,7 +263,7 @@ public class TestPlan implements IAggregate {
 		}
 		//start monitor to check the limit
 		UUID testPlanIdUuid = UUID.fromString(this.testPlanRunId);
-		if (getMonitors() != null) {
+		if (getMonitors() != null && this.limitModel != null) {
 			for (Monitor monitor : getMonitors()) {
 				monitor.start(testPlanIdUuid, this.limitModel);
 			}
diff --git a/Bench4Q-Master/src/main/java/org/bench4q/master/domain/service/TestPlanEngine.java b/Bench4Q-Master/src/main/java/org/bench4q/master/domain/service/TestPlanEngine.java
index 6229b84a..02773447 100644
--- a/Bench4Q-Master/src/main/java/org/bench4q/master/domain/service/TestPlanEngine.java
+++ b/Bench4Q-Master/src/main/java/org/bench4q/master/domain/service/TestPlanEngine.java
@@ -141,6 +141,7 @@ public class TestPlanEngine implements TaskCompleteCallback,
 					+ testPlanId.toString());
 			return;
 		}
+		testPlan.addObserver(this);
 		testPlan.run();
 		this.getTestPlanRepository().attachRunningTestPlan(testPlan);
 	}