1120：访问未定义的属性加载器

I have this code I'm trying to load a file .txt in my FLEX project. But something weird is happening, it's giving me this error, but the main point is... I ran this code in Flash using Dynamic text instead TextArea... and it runs perfectly, I'm starting to think that I have some problem with my FLEX software... Does somebody could help me, please.I have this code I'm trying to load a file .txt