Index: lams_common/src/java/org/lamsfoundation/lams/learningdesign/ToolActivity.java
===================================================================
RCS file: /usr/local/cvsroot/lams_common/src/java/org/lamsfoundation/lams/learningdesign/ToolActivity.java,v
diff -u -r1.44.2.5 -r1.44.2.6
--- lams_common/src/java/org/lamsfoundation/lams/learningdesign/ToolActivity.java	11 May 2016 07:07:21 -0000	1.44.2.5
+++ lams_common/src/java/org/lamsfoundation/lams/learningdesign/ToolActivity.java	15 Dec 2016 11:46:15 -0000	1.44.2.6
@@ -59,7 +59,7 @@
     private Tool tool;
 
     /** List of sessions associated with this ToolActivity */
-    private Set toolSessions;
+    private Set<ToolSession> toolSessions;
 
     private Set<CompetenceMapping> competenceMappings;
 
@@ -290,15 +290,15 @@
     /**
      * @return Returns the toolSessions.
      */
-    public Set getToolSessions() {
+    public Set<ToolSession> getToolSessions() {
 	return toolSessions;
     }
 
     /**
      * @param toolSessions
      *            The toolSessions to set.
      */
-    public void setToolSessions(Set toolSessions) {
+    public void setToolSessions(Set<ToolSession> toolSessions) {
 	this.toolSessions = toolSessions;
     }
 
Index: lams_common/src/java/org/lamsfoundation/lams/tool/service/LamsCoreToolService.java
===================================================================
RCS file: /usr/local/cvsroot/lams_common/src/java/org/lamsfoundation/lams/tool/service/LamsCoreToolService.java,v
diff -u -r1.45.2.11 -r1.45.2.12
--- lams_common/src/java/org/lamsfoundation/lams/tool/service/LamsCoreToolService.java	27 Sep 2016 06:22:54 -0000	1.45.2.11
+++ lams_common/src/java/org/lamsfoundation/lams/tool/service/LamsCoreToolService.java	15 Dec 2016 11:46:15 -0000	1.45.2.12
@@ -95,7 +95,7 @@
     public void setApplicationContext(ApplicationContext context) throws BeansException {
 	this.context = context;
     }
-    
+
     public void setActivityDAO(IActivityDAO activityDAO) {
 	this.activityDAO = activityDAO;
     }
@@ -152,7 +152,6 @@
 
 	// if haven't found an existing tool session then create one
 	if (toolSession == null) {
-
 	    if (LamsCoreToolService.log.isDebugEnabled()) {
 		LamsCoreToolService.log.debug("Creating tool session for [" + activity.getActivityId() + ","
 			+ activity.getTitle() + "] for learner [" + learner.getLogin() + "] lesson ["
@@ -162,11 +161,14 @@
 	    toolSession = activity.createToolSessionForActivity(messageService, learner, lesson);
 	    toolSessionDAO.saveToolSession(toolSession);
 
-	    return toolSession;
+	    // create a session on tool side within the same transaction,
+	    // otherwise core session can exist but tool's one not
+	    // and a learner entering an activity will get an error
+	    activity.getToolSessions().add(toolSession);
+	    notifyToolsToCreateSession(toolSession, activity);
 	}
 
-	// indicate that we found an existing tool session by returning null
-	return null;
+	return toolSession;
     }
 
     @Override
@@ -638,7 +640,6 @@
 	return null;
     }
 
-    
     @Override
     public Long getLessonMaxPossibleMark(Lesson lesson) {
 	// calculate lesson's MaxPossibleMark
@@ -652,7 +653,7 @@
 	}
 	return lessonMaxPossibleMark;
     }
-    
+
     /**
      * Returns lesson tool activities. It works almost the same as lesson.getLearningDesign().getActivities() except it
      * solves problem with first activity unable to cast to ToolActivity.