[Plugin: MM Forms] adding checkboxes?

I can’t seem to get the check boxes to show up. I tried using this code:

<h3>Please let me know what your interested in:</h3>

<p><label for="option1">[checkbox option1] In-House Consulting and Training</label></p>

The text shows up, but there’s no box.

http://wordpress.org/extend/plugins/mm-forms/