Have to reload page to see Flash, why?

I’m using PHP to send variables in the URL so that my Flash movie that is embeded in an HTML page shows a different frame according to which HTML page is called. However, each page has to be reloaded for the Flash to show, b/c on first load it is blank. I’ve checked all the syntax but can’t find the problem. Has anyone every encountered a problem with having to reload a page to see the Flash? Any help would be appreciated. Thank you.