An iFrame will literally display a URL in a frame. Your code doesn't seem to be a properly formed URL and may be the issue.
Are you able to copy the code as Amazon are telling you to insert it.
Instead of using the NetObjects iFrame tool, you might need to simply create a text box where you want it to display in NetObjects and then press CTRL+T and insert their code that way to display it. As an example of Amazon code you would copy and paste with the <iframe tags included. Example below:
Code:
<iframe src="http://rcm.amazon.com/e/cm?t=yourAssociatesID&o=1&p=13&l=ur1&category=home&banner=1KCJXE8FXDSDTBZ6SWG2&f=ifr" width="468" height="60" scrolling="no" border="0" marginwidth="0" style="border:none;" frameborder="0"></iframe>
You have also pasted your code and in part of that link it says =[my Amazon Affiliate ID] This is either a change you made to paste here or you need to change that as well.