Index: lams_tool_assessment/src/java/org/lamsfoundation/lams/tool/assessment/model/Assessment.java
===================================================================
diff -u -rdf5031224eb701a152c791bc8b4f4dee76fa1833 -r9aab81afe045c9bff18942543f6d960fe3ec6544
--- lams_tool_assessment/src/java/org/lamsfoundation/lams/tool/assessment/model/Assessment.java	(.../Assessment.java)	(revision df5031224eb701a152c791bc8b4f4dee76fa1833)
+++ lams_tool_assessment/src/java/org/lamsfoundation/lams/tool/assessment/model/Assessment.java	(.../Assessment.java)	(revision 9aab81afe045c9bff18942543f6d960fe3ec6544)
@@ -120,7 +120,7 @@
      * 
      */
     public Assessment() {
-	attachments = new TreeSet(new SequencableComparator());
+	attachments = new TreeSet();
 	questions = new TreeSet(new SequencableComparator());
 	overallFeedbacks = new TreeSet(new SequencableComparator());
     }
@@ -179,7 +179,7 @@
 	    // clone attachment
 	    if (attachments != null) {
 		Iterator iter = attachments.iterator();
-		Set set = new TreeSet(new SequencableComparator());
+		Set set = new TreeSet();
 		while (iter.hasNext()) {
 		    AssessmentAttachment file = (AssessmentAttachment) iter.next();
 		    AssessmentAttachment newFile = (AssessmentAttachment) file.clone();
Index: lams_tool_assessment/src/java/org/lamsfoundation/lams/tool/assessment/model/AssessmentAttachment.java
===================================================================
diff -u -r3fdcee6fa67ca8bbbf112bb01a95873fc76a6b0f -r9aab81afe045c9bff18942543f6d960fe3ec6544
--- lams_tool_assessment/src/java/org/lamsfoundation/lams/tool/assessment/model/AssessmentAttachment.java	(.../AssessmentAttachment.java)	(revision 3fdcee6fa67ca8bbbf112bb01a95873fc76a6b0f)
+++ lams_tool_assessment/src/java/org/lamsfoundation/lams/tool/assessment/model/AssessmentAttachment.java	(.../AssessmentAttachment.java)	(revision 9aab81afe045c9bff18942543f6d960fe3ec6544)
@@ -37,7 +37,7 @@
  * @hibernate.class table="tl_laasse10_attachment"
  * 
  */
-public class AssessmentAttachment implements Cloneable {
+public class AssessmentAttachment implements Cloneable, Comparable {
     private static final Logger log = Logger.getLogger(AssessmentAttachment.class);
 
     private Long uid;
@@ -79,6 +79,16 @@
 	return new HashCodeBuilder().append(uid).append(fileVersionId).append(fileName).append(fileType)
 		.append(created).toHashCode();
     }
+    
+    @Override
+    public int compareTo(Object o) {
+	if ((o != null) && o instanceof AssessmentAttachment) {
+	    AssessmentAttachment anotherAtt = (AssessmentAttachment) o;
+	    return (int) (fileUuid - anotherAtt.getFileUuid());
+	} else {
+	    return 1;
+	}
+    }
 
     // **********************************************************
     // get/set methods
@@ -151,4 +161,5 @@
     public void setCreated(Date created) {
 	this.created = created;
     }
+
 }
Index: lams_tool_assessment/src/java/org/lamsfoundation/lams/tool/assessment/web/action/AuthoringAction.java
===================================================================
diff -u -rabf33c38c735b09fa2eaa41b457cd278cffdcf01 -r9aab81afe045c9bff18942543f6d960fe3ec6544
--- lams_tool_assessment/src/java/org/lamsfoundation/lams/tool/assessment/web/action/AuthoringAction.java	(.../AuthoringAction.java)	(revision abf33c38c735b09fa2eaa41b457cd278cffdcf01)
+++ lams_tool_assessment/src/java/org/lamsfoundation/lams/tool/assessment/web/action/AuthoringAction.java	(.../AuthoringAction.java)	(revision 9aab81afe045c9bff18942543f6d960fe3ec6544)
@@ -356,15 +356,11 @@
 	List deleteAttachmentList = getDeletedAttachmentList(sessionMap);
 
 	// current attachemnt in authoring instruction tab.
-	Iterator iter = attachmentList.iterator();
-	while (iter.hasNext()) {
-	    AssessmentAttachment newAtt = (AssessmentAttachment) iter.next();
-	    attPOSet.add(newAtt);
-	}
+	attPOSet.addAll(attachmentList);
 	attachmentList.clear();
 
 	// deleted attachment. 2 possible types: one is persist another is non-persist before.
-	iter = deleteAttachmentList.iterator();
+	Iterator iter = deleteAttachmentList.iterator();
 	while (iter.hasNext()) {
 	    AssessmentAttachment delAtt = (AssessmentAttachment) iter.next();
 	    iter.remove();