Errors after changing from PHP 5.3 to PHP 5.4 or 5.5

Hi,

Today I changed my server's PHP version to 5.5.12 .
After that, I opened Zenphoto and the setup popped up, and everything went well.
But when opening albums in the admin panel, I get "Notice: Bad filename suffix in newImage()". And no photos are displayed.
The same happens with PHP 5.4.28.

Any help?

Thanks in advance.