Problems with relative paths while uploading

[eluser]semsemoo7[/eluser]
Hello,
I'm facing a problem with using relative paths while uploading using flash script (Uploadify) and when i set the path to upload it automatically convert it self to the root path of the site ! and my site is sub directory (eg.)(http://www.site.com/en/) , but when i use any path it automatically converted to the root Dir which referred to (http://www.site.com) .. i want the root directory after using relative paths refer to (http://www.site.com/en/) i don't know what to do with it

Another problem with the same matter , when i test the URL (http://www.site.com/en/upload/) and (http://www.site.com/en/upload) without trailing slash they gave me different paths.
Can i use both of them acting the same relative path?