diff --git a/libreplan-webapp/src/main/java/org/libreplan/web/montecarlo/MonteCarloController.java b/libreplan-webapp/src/main/java/org/libreplan/web/montecarlo/MonteCarloController.java
index ec2ed2a4d..543ca66ff 100644
--- a/libreplan-webapp/src/main/java/org/libreplan/web/montecarlo/MonteCarloController.java
+++ b/libreplan-webapp/src/main/java/org/libreplan/web/montecarlo/MonteCarloController.java
@@ -301,7 +301,8 @@ public class MonteCarloController extends GenericForwardComposer {
             feedCriticalPathsList();
             reloadGridCritialPathTasks();
         }
-        btnRunMonteCarlo.setDisabled(criticalPath.isEmpty());
+        btnRunMonteCarlo.setDisabled(monteCarloModel.getCriticalPathNames()
+                .isEmpty());
     }
 
     private static class CriticalPathTasksRender implements RowRenderer {
diff --git a/libreplan-webapp/src/main/java/org/libreplan/web/montecarlo/MonteCarloModel.java b/libreplan-webapp/src/main/java/org/libreplan/web/montecarlo/MonteCarloModel.java
index 6fbc6fd56..4d6cd2c4e 100644
--- a/libreplan-webapp/src/main/java/org/libreplan/web/montecarlo/MonteCarloModel.java
+++ b/libreplan-webapp/src/main/java/org/libreplan/web/montecarlo/MonteCarloModel.java
@@ -84,6 +84,9 @@ public class MonteCarloModel implements IMonteCarloModel {
             return;
         }
         this.tasksInCriticalPath = onlyTasks(tasksInCriticalPath);
+        if (this.tasksInCriticalPath.isEmpty()) {
+            return;
+        }
         Collections.sort(this.tasksInCriticalPath, Task.getByStartDateComparator());
         initializeTasksInOrder(getOrderFor(this.tasksInCriticalPath));
         initializeOrderNameFor(this.tasksInCriticalPath);