Did you add a parameter to a family but when you loaded the family into your project the new parameter won’t schedule or show up in your tags? You have to make it a Shared Parameter.
Creating the Shared Parameter File:
1. While in Revit (doesn't matter if you're in a family or project file) go to File... Shared Parameters... Create... give the txt file a name. This shared parameter file can be used on all your office's projects if you wish. Now Create Group... and add parameters you want to see in schedules or tags. The Shared Parameter file is now loaded into your Revit session for use in other family or project files.
Adding the shared parameter to your family and project files:
1. While in your family editor go to Family Types... Add Parameter... Shared Parameter... and Select your new parameter. Now while in your project file go to the schedule you want the parameter to show up in and go to View Properties... Fields... Add Parameter... Shared Parameter... and Select your new parameter.
2. If you're adding a parameter to your tags... While in your project file go to Settings... Project Parameters... Add... Shared Parameter... and Select your new parameter. Don't forget to check which family category to apply the Shared Parameter to.
If you exit all your Revit files but leave Revit running you will see that under File... Shared Parameters your shared parameters file is still loaded for use in other family or project files.
For more on Shared Parameters search Steve Stafford's RevitOpEd.