             }
             else
             {
-                angleTo = (!isNaN(angleBy)) ? angleFrom + angleBy : 
-                    getCurrentValue("rotation");
+                if (!isNaN(angleBy) && !isNaN(angleFrom))
+                    angleTo = angleFrom + angleBy; 
             }
         }
         

            else if (propertyChanges && 
                propertyChanges.start["rotation"] !== undefined)
                angleFrom = propertyChanges.start["rotation"];
            else
                angleFrom = getCurrentValue("rotation");
        
        if (isNaN(angleTo))
        {

        newY = Number((centerY - originalOffsetY).toFixed(1)); // use a precision of 1
 
        propertyValuesList = 
            [new PropertyValuesHolder("rotation", [angleFrom, angleTo], angleBy)];

        super.play();
    }
