Contact form 7 two columns layout not working with all templates?

I build a two column contact form that looked fine when I use the Twenty Eleven theme.
When I select another theme (e.g. Weaver ii or Mantra) everything is back in one columns.
Why is this happening?

This is the code I used:
<div id=”two-column”>
<div id=”left”>
<p>First Name [text* first-name]</p>
<p>Email [email* your-email] </p>
</div>
<div id=”right”>
<p>Last Name [text* last-name] </p>
<p>Phone [text* your-phone] </p>
</div>
<p>Subject [text* your-subject] </p>
<p>Your message [textarea your-message]</p>
<p>[submit “Send”]</p>
</div>

http://wordpress.org/extend/plugins/contact-form-7/