Please help me, HSC major project, urgent

Question

Hi,
I am doing an interactive storybook for a HSC project. I am trying to code for it and it is telling me two error messages. These are 1120: Access of undefined property. I tried to insert a screenshot but it wont let me in this question. Maybe I message individual people the screenshot ?
How do I fix this error message ?
here is my code:
stop();
Page1_btn.addEventListener(MouseEvent.CLICK,turnpage2);
function turnpage1 (evt:MouseEvent):void {
  screen_mov.gotoAndPlay ("Page2");
  page1_btn.visible = false;
So the pages are numbered starting at 1, 2,3 3, 4, 5, ..............................
Screen_mov is the movie clip for the project containing all the pages/ graphics
and page1_btn is the button for page 1
PLEASE HELP THIS IS URGENT !

Answer 1

Hi,
I am having further troubles. In my storybook on the first page all the buttons are appearing, I do not want this. How do I code to fix that, the only button I want on the first page is "page1_btn"
will paste my coding into here, and could you please tell me what to do to fix this ?
page2_btn.visible= false;
p3_first_btn.visible= false;
page1_btn.addEventListener(MouseEvent.CLICK,turnpage2);
function turnpage2 (evt:MouseEvent):void {
  screen_movie.gotoAndPlay ("page2");
  page1_btn.visible = false;
page2_btn.visible= true; 
page2_btn.addEventListener(MouseEvent.CLICK,turnpage3);
function turnpage3 (evt:MouseEvent):void {
screen_movie.gotoAndPlay ("page3");
page2_btn.visible= false;
p3_first_btn.visible= true;
p3_first_btn.addEventListener(MouseEvent.CLICK,turnpage3a);
function turnpage3a (evt:MouseEvent):void {
screen_movie.gotoAndPlay ("page3a");
p3_first_btn.visible= false;
And, also the reason why I am setting the buttons to visible= true; at the start and visible= false; at the end is because I can only have one button for each page.
Please help someone,
Regards,
Adam