If you have created or refreshed a sandbox based on your production environment where Booker25 is installed, the configuration will probably not have copied over correctly. This goes for all sandboxes except Full Copy sandboxes. This article explains the steps you need to take in order to reset configuration to the defaults, as if Booker25 was just installed.
This process will delete all records of Booker25 objects! Only perform this operation if the org does not have any data in Booker25 objects that you want to preserve.
The list of objects that will be deleted:
Any custom objects that you may have created, and that are details of any of the above objects in a Master-Detail relationship
Steps to perform
Go to Setup> Custom Settings
Click Manage next to System Settingwith B25 in the Namespace Prefix column
Fill in Name field as follows: 'removeAllBooker25Data'
Fill in the String Value as follows 'Yes, I want to remove all Booker25 data'
Click on the wheel in the top right and then Developer Console
In the new window, click Debug in the menu bar
Click Open Execute Anonymous Window
Copy and remove any existing text that may be there and save it somewhere, so it can be accessed again later if required
Paste B25.Util_SandboxSetup.removeAllBooker25Data(); and press the Execute button
Remove the previous line, paste B25.Util_PostInstall.doFreshInstall(); and press Execute
You have now successfully performed a fresh Booker25 install