Piwik tracks only the siteId=1 (no replies)

Hi,

I've two websites on a pubblic server, the first one is tracked but not the second. I've added the tracking code with a cut/paste from piwik config section.

Chrome inspector shows an error for piwik.js request on siteid=2, request fails and the status is "pending".

SiteId=1 http://cen.isprambiente.it/
SiteId=2 http://agentifisici.isprambiente.it/

Any hints?
Regards

PS server is debian/linux, apache2.2