CKEditor 4 library is not detected by Wysiwyg module
The WYSIWYG module is not compatible with CKEditor 4, because CKEditor 4 uses double quotes " around it's version string, where CKEditor 3 used single quotes '. This breaks the version detection regex in the WYSIWYG module.

You could use CKEditor 3, like Bruno suggests, or you could patch the WYSIWYG module like described here https://drupal.org/comment/6790812#comment-6790812.

In editors/ckeditor.inc, replace line 81:

if (preg_match('@version:\'(?:CKEditor )?([\d\.]+)(?:.+revision:\'([\d]+))?@', $line, $version)) {


with:

if (preg_match('@version:[\"|\'](?:CKEditor )?([\d\.]+)(?:.+revision:[\"|\']([\d]+))?@', $line, $version)) {


If you're not bound to using the WYSIWYG module, you could also use the CKEditor module.