gravity forms issue

When I use a gravity forms shortcode with ajax enabled in a popup, the confirmation text displayed on submitting the form just flashes by as the popup closes.
How can I make the popup stay and let the user close it instead?

If I disable ajax in the gravity form shortcode I get to a 404 page instead.

[gravityform id=”7″ title=”true” description=”true” ajax=”true”]

Thanks for any help!