I've got an issue with album/category thumbnails not showing ... Here's what I do. I create an album through the admin plugin interface. Then I have to erase / recreate / reCHMOD to 777 the album folder (as discussed in another thread). Then I upload through FTP client the images for the specific album. When I go to album list and then inside the specific album, I can see correctly the images (they are shown correctly as well with the gallery user interface). Until here : no problem. :) But, in some cases (not every time !) it is just impossible to set an image as album/category thumbnail (the default "corrlete lab bird" image is showing instead). Even though the admin plugin interface says the image has been set as thumbnail for the album, it does not show as album thumbnail. And when I try to do it again ... a message says the image is already defined as album thumbnail. Strange, isn't it ? :) I'm trying, by comparing different cases, to find a common reason for album/category thumbnails not to show but I can't find a clue.
I think I know the reason - your picture file names should containt only a-z, 0-9, - and _ characters. The problem comes because you are uploading direct with FTP and you are not using the Gallery upload interface. I understand the reason for that - you have safe mod enabled on your server.
e107 Bulgaria | Corllete Lab
And thanks for your quick answer. :) After a few tests, I know the reason now : the image filename was too long. When renaming from something like 65 characters long to 20 characters ... I can select this image as thumbnail for album. I don't know the exact number of characters limit but this was clearly the problem.
I just checked ... The image filename characters size limit seems to be : 46 characters for the name + 1 character for the dot + 3 characters for file extension. 50 characters in total maximum.