Symptom:
You get "name in use" when trying to remove bindings. It works for certain names but not for others.
Possible Cause:
You cannot unbind the name of a context. This restriction is in place to avoid leaving behind contexts that have no name ("orphaned contexts").
Diagnosis:
Run the fnlist command on the name to verify that it is a context.
Solution:
If the name is a context, use the fndestroy command to destroy the context.