Flash in Firefox is not displaying

Question

I use Open Flash Chart on my web and in Chrome it displays perfect, but in FF it just isn´t visible, there´s nothing. Any suggestions what to do with this? Is it some sort of bug?

var cesta = encodeURIComponent("./safe/kalkulace_graf1.php?k_polozka=<? echo $co; ?>&tit=false");
swfobject.embedSWF("./open-flash-chart.swf", "nahledGrafu", "400", "102", "9.0.0", "expressInstall.swf", {"data-file": cesta } );

<div id="nahledGrafu" width=200 height=100>
    <a href="http://get.adobe.com/cz/flashplayer/?no_redirect">
        <img src="../obrazky/flash-player.jpg" style="margin-left:115px" height="100" alt="Chybí Flash Player" title="Nemáte zapnutý nebo nainstalovaný Flash player.">
    </a>
</div>