Documentation for Backup up CCS ADAM (AD/LDS) shows the following.
filesAt step 5 the instance of ADAM has not yet been set, so you will get the message "Active Instance not set. To set an active instance use "Activate Instance "."
After step 4 run the following command to set the active instance.
activate instance symantecccs
After that command has been run the following steps will work without further errors as long as the services have been stopped.
For Example: