Flash player 5 discrepency with instance names in mc's & dynamic text?

ok, i have a movieClip with the instance name “content” within it I have a dynamic text field with the instance of news_txt which calls for an outside .txt document for its content, but when I try to publish the swf it gives me an error saying:

WARNING: This movie uses features that are not supported in the Flash 5 player
Symbol=content, layer=content, frame=1:Flash MX Text Field Instance Name

wtf? this is my script within the mc,

var externalData:LoadVars = newLoadVars();
externalData.onLoad = function(){
    news_txt.text = externalData.newsContent;

so what am I doing wrong? thanks.