Banner code snippet in Navigator : gif won't show

As with many other code snippets for inserting ad banners on simple html sites, I designed code whose significant part for Navigator looks like this :
<a href="navlink.cfm" target="_top">
<img src="navimg.cfm" border=0 alt="">
</a>

where navimg.cfm gives way to a randomly selected gif banner while navlink.cfm registers clicks before branching the user to the target site.

This works perfectly well when inserted in a basic page structure, but won't when the snippet is put inside any table cell :

<table>
<tr>
<td>
<a href="navlink.cfm" target="_top">
<img src="navimg.cfm" border=0 alt="">
</a>
</td>
</tr>
</table>

Any one knows why ?

Limitations because of this are such that banners can only be displayed "rejected" above or beneath pages.

I am not a Cold Fusion expert, but my guess is that there is some limitation to how deep can you "burry" the code...

I'll have a try with Php then. The technique is used by almost all ad server sites (perl, asp, php) so if it does work with Php, it should be a limitation on Navigator (ok in IE), not Cold Fusion. I'll keep in touch.