Arrays from external text files

I’m using LoadVars to load an external file that has one variable containing an array with a few sub arrays. here is the code i have:

var externalData:LoadVars = new LoadVars();
externalData.onLoad = function() {
	var sectArray:Array = externalData.sectArray;

But every time i try to get one of the values i get “undefined”. is there another way?

Thanks, Brendan Smith