def ScrollUp(self, units):
         """Move view up number of axis units."""
         self.last_PointLabel = None        #reset pointLabel
-        if self.last_draw is not None:
-            graphics, xAxis, yAxis= self.last_draw
-            yAxis= (yAxis[0]+units, yAxis[1]+units)
-            self.Draw(graphics,xAxis,yAxis)
+        if self.BeenDrawn():
+            self._drawCmd.scrollAxisY(units, self._ySpec)
+            self._draw()
         
     def GetXY(self,event):
         """Takes a mouse event and returns the XY user axis values."""