document.write works in IE but not firefox?

[celeroSolutions]

This code works in my site in IE, but not in FireFox, and I'm stuck as to why! Any ideas? (The image paths are correct, I've tested these.)

<script language="javascript" type="text/javascript">
 
<!--
 
var strBGCol = "#ADCED7";
 
document.write("<table border='0' width='100%' cellpadding='0' cellspacing='0'>");
document.write("<tr>");
 
//Load the default CU images into the table
document.write("<td id='banner_lhscell' align='left' width='25px'>");
document.write("<img id='banner_lhsimg' src='" + strImgDirPath + "lhsban1.jpg'>");
document.write("</td>");
 
document.write("<td id='banner_ctrcell' align='center' bgcolor=" + strBGCol + ">");
document.write("<a href='/_layouts/login.aspx?ReturnUrl=%2fPages%2fadmin.aspx' target='_blank'>");
document.write("<img id='banner_ctrimg' src='" + strImgDirPath + "ctrban1.jpg' border='0'>");
document.write("</a>");
document.write("</td>");
 
document.write("<td id='banner_rhscell' align='right' width='25px'>");
document.write("<img id='banner_rhsimg' src='" + strImgDirPath + "rhsban1.jpg'>");
document.write("</td>");
 
document.write("</tr>");
document.write("</table>");
 
-->
 
</script>

[gits]

could you please specify what is exactly not working? where does strImgDirPath come from?

kind regards