PortalApp working on Preview but not on Portal

Hi everybody!

I'm facing a real very strange situation. I've developed a PAR, which contains two Components. One of them calls the other using AJAX & Prototype. I've tried it on my own machine, and works perfect. I've upload the par to the server which will contain the Portal, created an IView for the par, a Page for the IView, and the preview works fine. But the page doesn't work on the portal. The AJAX request fails, and doesn't reach the server....

We're connecting the server via VPN.Can that be a problem?

Thanks in advance, and sorry for my terrible english.

Eneko