executing a dom script in a xsl stylesheet

hi, my problem is that if i execute an external script that add some 
nodes to the document (/element/.appendChild(/node/)), mozilla  (Firefox 
1.0) ignores the format, it appends just the text, no matter tags (<p>, 
<br />...)

I tried also /element/.innerHTML, and i got the same result

Using document.write(), i got nothing, neither the text

One extra effect i got is that the image that fill the background 
doesn´t fit perfectly: the borders are white

All of these thing work properly in IE6


Could someone suggest something??


Thanks