Support pointed out there was a problem with my php configuration and after my host changed it, it still didn't work because my php had some troubles with XML configuration. These guys changed their code so it still support my server. They even go further. I asked them what they wanted me to pay for extra functionality and they make this functionality for free! Now everyone can display the album cover from a picasa album and when clicking seeing all the pictures in the album. A pity Picasa xml feeds are a bit slow so you can't use too much albums on one page.
Nevertheless a wonderfull service and this for only 15$!!!