Image/Media Uploader problems …but only on Custom Post Type posts

Hi, my name is Paolo, writing from Italy. Recently I’m having problems on custom post types: I try to upload image using the Media uploader, but when I click to “Insert to post” button, the panel remain blank and the image do not appear on TyneMCE editor (while the image appear in the Gallery list). This do not happen using the normal/blog posts, only on custom.

I’ve tried the various procedure I find here and on the web (reload the original wp-admin and wp-include, insert mod_security.c code in the htaccess file, and others) but there’s noting for it.

The custom posts I’ve created was working fine, never had this problem, but after various some tweaking and security plugins, but now I can’t figure out where’s is the problem

Any clues or suggestions?

Thans
Ciao
Paolo