Colorbox isn't working, although all settings are correct
Try the following with colorbox:


Do you have the latest version? If you updated recently to version from colorbox notice that in the module page says Changes since 7.x-2.1: Important: When updating to this version of the Colorbox module you need to update the Colorbox plugin to v1.3.21.1 or later as well.
Mohammed Shameem mentioned in the comments above is valid. He remark the following: please note that colorbox 1.3.26 and 1.3.27 had an error due to which the script was not working with older version of jQuery so you should download the latest version.


However, the version of colorbox included in the Drupal 7.x colorbox module is NOT STATED.