Adding my simple javascript is breaking my add to cart

Why would adding

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.

... because you're likely putting your extra form between existing <form> and </form> tags, thus breaking the existing add-to-cart form already on the page.

I can't see that this is the case. EXCEPT for the fact that at the end of the page in tpl_product_info_display.php (on my version and on the default version)
there is

Any idea if this is the cause or how to solve, there is no <form> on the page.

Earlier on the page is the following, but I don't think it would have any relevance.

reads like this when viewing source:

so I guess that would be the front form I could not find.

That being said, I can put:

into the page where I want and double the </form> at the very end of the tpl_product_info_display.php like this

is there any reason that this would be unadviseable?

Why do you need any <FORM> and </FORM> tags at all? After all, you're already inside a form anyway, right?

I removed the extra <form></form> and everything still works. I did it that way because it was the way the example code was shown. Thank you for the help, I appreciate it.