window.parent.frames

Hi, I am having issues getting this code to work, I done repeated seaches to help solve my issues
this is a section of code from an electronic service manual. It works on an old xp laptop i kept for emergencies but doesn' seem to work on w7
with the new IE. I've resolved it to old code. The manual over all works, with exception to some key navigation buttons. When i run F12 debugger I
get ;
SCRIPT5002 FUNCTION EXPECTED
 When I search the error i get an advance trouble shooter which I have problems relating thier vague code examples to my situation. 
The problem seems to lie in this line of code and others similar but I' unsure of the cause;

var ln1 = window.parent.frames('content').document.links.length - 2

Here's the full *string for this one navigation button *(please excuse if terminology is wrong )
function nextPG(){ cont=0 var ln1 = windo ...