Hi Jenna,
A form will not prepopulate if it is on a landing page or if it is embedded anywhere. It must be linked directly from an email to the form for this to work. Use the hyperlink manager in the email template designers and choose Web Content > Profile Management Form > and choose the one you want.
If you're not trying to prepopulate, you are just trying to get a form to appear on a landing page and it is not working, please open a support ticket and our team will help you with that. http://support.clickdimensions.com.
Thank you!