The import statement needs to be within <% ... %> too, or replace Level with java.util.logging.Level
Sorry David, I did not show this above, but it is within <% ... %>, so something else gives the error message.
So, what do you get if you write:
<%
if (folderBeforeImage) {
JAlbum.logger.log(java.util.logging.Level.SEVERE, "You should re-arrange your images and/or videos in folder {0}, so that the folders are located after all normal images and videos in the jAlbum Explorer", currentFolder);
%>