ActionScript 3.0 :: Get Next And Previous Buttons To Work?

I'm building an XML photo gallery and I'm trying to get next and previous buttons to work. Here is the code I am working with.

Code:
function loadTheThumbs(){
var thumbLoader:Loader = new Loader();
var thumbRequest:URLRequest = new URLRequest (thumbPathList[c] );

[code]....

I have written the nextPhoto function based on the loadExtPic function above and that does indeed load the function. The problem is, when I want to advance to the next image, I can't because I can't find how the currently selected image is set. When you click on a thumbnail the

Code:
var thisThumbsLink:String = picturePathList[c];

is set to the correct image, but I can't seem to see in the code where the "c" is coming from. I tried adding a

Code:
var LoadedPicture:String = picturePathList[c+1];

right under the thisThumbsLink var to no sucess. If I can figure out how, when you click on a loaded thumbnail it knows which thumbnail is loaded, then I can take that and make a next and previous link var as well in the same fashion the thisThumbsLink works.