Swf loading problem!

I have a movie clip that I am loading an external swf into. When I publish preview inside of Flash it shows up correctly and everything is great. The swf is loading into the correct mc, and it looks just as I had intended. Now the problem is, when I publish both files and put the two swfs up on the web, the file is no longer loading into the clip and it is not showing up. If I open up the main swf inside of flash, it looks great. But whenever I view it outside of flash it doesn’t work. What am I doing wrong? Somebody, please help, this is driving me crazy!!! Thanks!