submiting changes issue

I cannot save changes with the editor. I've looked ad the samples and faq. Nothing seems to work.

I've got simple code:

        <form action="index.php" method="post" >
            <textarea name="editor1" id="editor1" rows="10">
                This is my textarea to be replaced with CKEditor.
            </textarea>
            <input type="submit" value="ok"/>
        </form>  
                             
        <script>
           CKEDITOR.replace( 'editor1' );
        </script>

and everytime i submit do changes and submit it revert back to the start text... ive tried to move the script inside and outside the form but the result is the same. Any idea what should i hange to make it work?