Flex file upload to remote server using PHP

I am trying to upload the files to the remote server using PHP with Flex interface. If it's not localhost, it shows the security error. I have already put the crossdomain.xml in the tomcat web app root direc开发者_如何学JAVAtory to allow all the domains. However, the security error is still shown when I tried to upload the file. Any suggestion for this problem? Thanks.

If you're running your swf from local sandbox, add the location (you're running it from) here.