Problem embeding swf in index.php

[panoss]

I'm trying to embed an swf file in a .php file.
When both files (php & swf) are in the same directory (mysite.com/), works perfectly.
Here is the code I put in php file (mysite.com/my.php)(some is replaced by 'blah blah' or erased, for short):

<object classid=blah blah...codebase=blah blah...>
<param name="allowScriptAccess" value="sameDomain" />
<param name="movie" value="my.swf" />
<embed src="my.swf"  type="application/x-shockwave-flash" pluginspage="http://www.macromedia.com/go/getflashplayer" />
</object>

But when I move 'my.swf' in 'mysite.com/mydir' it doesn't work (even though I change the path in the code):

<object classid=blah blah...codebase=blah blah...>
<param name="allowScriptAccess" value="sameDomain" />
<param name="movie" value="mydir/my.swf" />
<embed src="mydir/my.swf"  type="application/x-shockwave-flash" pluginspage="http://www.macromedia.com/go/getflashplayer" />
</object>

I also tried:
'/mydir/my.swf'
'./mydir/my.swf'
'mysite.com/mydir/my.swf'.
Nothing. Worked only when in 'mysite.com/'.