Ok, then we ask the usual question: what is showing up in your PHP error logs?

The error logs within ZP say nothing about this.
I tried to modify the first entry in the cache settings (admin), but no modifications are saved.

We mean of course as well the php error log. The zp log does not always get everything.

I don't have access to this, but I just asked my webhoster and he will look into it.

You don't have access to your server error log, not even through your host's backend maybe? That is really unfortunate and should really be available in some way.

My host took a look for me in the log files, but couldn't find any reference to ZP in any way. The problem has to be somewhere within the plugin or something I did perhaps to the theme, althought my theme is quite straight forward really.

Here you can see that all images are not indexed:
http://ompldr.org/vZmkybw/Selectie_029.bmp

And here that the errors start with the images:
http://ompldr.org/vZmkycA/Selectie_030.bmp

And here the errormessage itself (missing xml tag):
http://ompldr.org/vZmkycQ/Selectie_031.bmp

I have no idea were to look further. None of the images are indexed in Google, either way, with or without sitemap .

This is my code in image.php: printDefaultSizedImage(getImageTitle())
and all my images have been cached, although they show up rather small in size, but that's because (I guess) because my larger images are already the right size:

http://ompldr.org/vZmkydQ/Selectie_033.bmp

One of the screenshots as far as I understand notes an xml error in the image sitemaps. So how does that look like and what is it actually it is complaining about?

The imagemaps all look the same, like this:

http://ompldr.org/vZmk0NQ/Selectie_034.bmp

and then there is a reference to this:

http://ompldr.org/vZmk0OQ/Selectie_036.bmp

And Google is always complaining there is a xml tag missing:

http://ompldr.org/vZmk0OA/Selectie_035.bmp

Yes, indeed the actual image links are missing and I can confirm I indeed can reproduce that on my live test install. http://support.google.com/webmasters/bin/answer.py?hl=en&answer=178636
Now we have to find out why that got broken.

However, Google really should also index the image itself via the albums and the site itself...

Anyway I opened a ticket for it: http://www.zenphoto.org/trac/ticket/2245 All further discussion regarding test there.

Thanks! I will follow the comments there and test any changes that are suggested.

Funny, I just wanted to let you know how things are now and got the message the ticket is closed for this 'problem'. Never mind, I just wanted to let you know that the sitemap probably works fine, but that even after seven weeks the images are slowely being indexed. In this image you can see the WordPress sitemap and the ZP sitemap, split into a web part and an images part. The web part (I assume these are the .php extensios) are indexed much better than the images themselves:

http://ompldr.org/vZ2YzbA/Selectie_196.bmp

Did you submit index.php?sitemap to Google? Try to submit the actual main sitemap index file directly. Maybe that makes the difference.

Good thinking. I'm going to try that.