Problem with the document class

[lope]

I have movieclip in the library with export name: TxtPreloader

in my document class (of that fla which is in the same package as the fla file) i have written this:
import TxtPreloader;

but when I try to instantiate that document class from somewhere else i get an error :

1172: Definition TxtPreloader could not be found. import TxtPreloader;