All right, I actually found what is the problem. It's related to the type of user. Initially the user was part of Registered users group, then I moved it to Author and now I get the page displayed properly!
Hmmm...
I found it's permission related after reading this on Internet
==============
Fatal error: Call to a member function get() on a non-object in
\plugins\editors\tinymce.php on line 433
error because the object that the statement try to call is not an object,
on line 422 of this file call to the JEditor::getButtons()
on line 261 of the editor.php the code is not right
$result[] = $plugin->onDisplay($editor);
because the register doesn't have the right to have the image button, so the
function $plugin->onDispaly($editor) when the $plugin is 'plgButtonImage'
will return the null this will lead to the error above.
solution is replace the line
$result[] = $plugin->onDisplay($editor);
with
$temp = $plugin->onDisplay($editor);
if ($temp) {
$result[] = $temp;
}
=============
I didn't implement the code change I just changed the role of that user, but still I don't want all my registered users to be Authors, what should I do? Any ideas...

