最近在使用PHP File Hosting Site Script，在启用Image Viewer插件后发现一些问题，比如上传文件后显示出错信息，无法显示下载地址，以及生成的缩略图太小等等，查看系统日志后，发现一些出错信息。

( [Error Msg] => Call to undefined function getCoreSitePath() [File] => /plugins/imageviewer/includes/_append_class_uploader_success_result_html.php [Line Number] => 24 [Error Type] => E_ERROR ) ( [Error Msg] => Call to undefined function sqlDateTime() [File] => /plugins/imageviewer/site/thumb.php [Line Number] => 73 [Error Type] => E_ERROR )