You have setup all your formulae & they have been working in the past but no longer work at all.
Check that the sandboxed Asyncronous Windows service is running. You can check this by going to the server that you have installed Microsoft Dynamics 365 2011 on & checking its list of Windows services that the one named "Microsoft Dynamics 365 Sandbox Processing Service" is started. If it is not started then start the service.
Did you know?
xCache helps you manage environment specific configuration
North52's Decision Suite component xCache allows you to set up environment specific data to allow you to use different values for different instances. Your advanced business rules logic could be the same, however you need to use specific reference values for a particular instance.
For example, credentials for a web service used in your Formula - you will likely use different keys/URLs for your Dev, Test and Production instances. Store these in xCache and let the North52 business rules engine apply the correct ones at runtime!