Title is clear: my host is 1and1, I've added the proper line in my .htaccess in order to use PHP5, and yet I see no thumbnail (only the full size images are available). What did I do wrong?
Thanks in advance

Did the setup complain about anything? Additionally please review our troubleshooting post on our user guide section. Most likely your images are too big for your server to process.

Setup didn't complain, but at setup time I had not made the modification in .htaccess, so it was PHP4. Is that a problem?

I've had a look at the troubleshooting, it didn't help (well, it did, but not for this issue!).

My images are quite large indeed. What's the limit? If it depends on my configuration, where/how can I find it?

Thanks anyway for your answer.

Zenphoto should run with both php 4 and 5 (I use 5 though). You need to ask your host about the php memory limit. Please also read: http://www.zenphoto.org/2008/08/troubleshooting-zenphoto/#11

Thanks for all the info, I could find the right picture size and everything's now OK. Thanks a lot.