Setting frame of a movie clip within a group - can't get it to work

Any idea why this code will not work to set the frame of a movie clip within a group?

  
achievementsPanel = display.newGroup()  
achievementsPanel.x = 8  
achievementsPanel.y = 483  
  
local achievement1Icon = movieclip.newAnim{ "images/achievementBall.png", "images/achievementBallBlank.png"}  
  
achievement1Icon.x = 28  
achievement1Icon.y = 110  
  
achievementsPanel:insert(achievement1Icon)  
achievementsPanel[1]:stopAtFrame(2)  

I was able to set the visibility of the movie clip as follows:

[code]

achievementsPanel[1].isVisible = false

[/code] [import]uid: 7863 topic_id: 4549 reply_id: 304549[/import]

Ah sorry, i had the wrong index value and have sorted this now… [import]uid: 7863 topic_id: 4549 reply_id: 14337[/import]