Why would adding

<br class="clearBoth" />
<br><br>
<center><FORM>
<INPUT TYPE="button" VALUE="Add to Favorites" onClick='window.external.AddFavorite(location.href, document.title);'>
</FORM></center>

between bof and eof anywhere above <!--eof Add to Cart Box--> on tpl_product_info_display.php

break my add to cart button, nothing happens. It does not matter where I put it. I have rearranged the page a lot, but all of the sections are complete.

The add to favorites that the java creates works, but it breaks the cart. Is this a common bug? I was trying to add it after my short description. I tried with and without <br class="clearBoth" /> and it does not make a difference.

I can put it under <!--eof Add to Cart Box--> and it works ok??
Thanks for any help on the matter.

Zen cart 1.3.8a
attribute_popup_large_images_1-0-3 and short description are the add ons that are related to this page.