*** QuickLaTeX cannot compile formula:
\begin{tikzpicture}  \begin{axis} \addplot3[surf,domain=0:360,samples=400] {cos(x)*cos(y)}; \end{axis} \end{tikzpicture}

*** Error message:
Cannot connect to QuickLaTeX server: cURL error 28: Operation timed out after 40001 milliseconds with 0 bytes received
Please make sure your server/PHP settings allow HTTP requests to external resources ("allow_url_fopen", etc.)
These links might help in finding solution:
http://wordpress.org/extend/plugins/core-control/
http://wordpress.org/support/topic/an-unexpected-http-error-occurred-during-the-api-request-on-wordpress-3?replies=37