A couple of questions:
- Which AJAX library are you using?
- What method are you using to fetch the content from CKEditor?
I use jQuery + validate (form validation plugin) for my form submissions.
The textarea to which CKEditor is bound is named body.
For some weird reason when I submitted the form, the content wasn't being submitted at all. Looking into the HTML I found that the textarea wasn't being populated by CKEditor (don't ask me why).
What I did was to just prior to submission, manually grab the data from CKEditor and stash it into the textarea. A single line of jquery should suffice.
$( '#body' ).val( CKEDITOR.instances.body.getData() );
And then proceed with the form submission normally. jQuery has a very good data serialization method - a function called serialize(), which I use to convert the entire form's data into a string. At the PHP end, this string is auto-converted into members of the $_POST array.
You should try the same approach and see if it works for you.
If you're still stuck, post your code here.
Cheers,
m^e