diff --git a/om/src/packages/basic/containers/data-stream.lisp b/om/src/packages/basic/containers/data-stream.lisp
index 78b177341..283402c07 100644
--- a/om/src/packages/basic/containers/data-stream.lisp
+++ b/om/src/packages/basic/containers/data-stream.lisp
@@ -74,7 +74,9 @@
 (defmethod (setf frames) (frames (self data-stream)) (setf (slot-value self (data-stream-frames-slot self)) frames))
 
 (defmethod data-stream-get-frames ((self data-stream)) (frames self))
-(defmethod data-stream-set-frames ((self data-stream) frames) (setf (frames self) frames))
+(defmethod data-stream-set-frames ((self data-stream) frames) 
+  (setf (frames self) frames)
+  (time-sequence-update-internal-times self))
  
 ;;; TIME-SEQUENCE API
 (defmethod time-sequence-get-timed-item-list ((self data-stream)) (data-stream-get-frames self))
diff --git a/om/src/packages/basic/time-sequence/time-sequence.lisp b/om/src/packages/basic/time-sequence/time-sequence.lisp
index fb3c95df5..86b7d757a 100644
--- a/om/src/packages/basic/time-sequence/time-sequence.lisp
+++ b/om/src/packages/basic/time-sequence/time-sequence.lisp
@@ -331,7 +331,9 @@
     ))
 
 
-;todo clean and avoid calls to om-copy
+; todo: 
+; - clean and avoid calls to om-copy
+; - simplify when all points have a time !!
 (defmethod time-sequence-update-internal-times ((self time-sequence) &optional (interpol-mode :constant-speed) (duration 10000) (modif-time nil))
   ;this function creates a list of times for all timed points even if they are nil.
   ;It can do with constant time or constant speed interpolations (interpol-mode :constant-speed :constant-time "default")
diff --git a/om/src/packages/sound/sound/sound.lisp b/om/src/packages/sound/sound/sound.lisp
index 7e3a42931..21e83261c 100644
--- a/om/src/packages/sound/sound/sound.lisp
+++ b/om/src/packages/sound/sound/sound.lisp
@@ -231,7 +231,8 @@ Press 'space' to play/stop the sound file.
 (defmethod (setf markers) (markers (self sound))
   (data-stream-set-frames 
    self
-   (mapcar #'(lambda (m) (make-instance 'marker-frame :date m)) markers)))
+   (mapcar #'(lambda (m) (make-instance 'marker-frame :date m)) markers))
+  markers)
 
 ;;;===========================
 ;;; INITIALIZATION...