When view your post/page code, what do you see? For your default

(first) form there should be a just a

<!–cforms–>

tag (no numbers).

There is also the slight chance that some other plugin (or WP) strips out comment tags from your post/page code.

enter the above placeholder in CODE VIEW and it will work

From the Help page: 

2.Inserting a form

In posts and pages:

Please use <!–cforms–> for the first form and/or <!–cformsX–> for your other forms to include them in your Pages/Posts. You can apply the aforementioned code either manually or via the editor button (if turned in the Plugin Settings).

Since this is code, you need to either  switch to code view first and insert manually or user the button and enter nothing for the default form or 2 for instance for your second form to show up.