how to enable voice isolation for users in teams

Hi

I'm trying to enable voice isolation for a single user in teams. I'm set my teams admin in Azure and connected the teams module in powershell. I'm running the below command
Set-CsTeamsMeetingPolicy -Identity "xxxx.xxxx" -EnrollUserOverride Enabled
which i believe should enable the voice recogntion option for the user and therefore allow use of voice isolation . However, i keep getting this error

Set-CsTeamsMeetingPolicy : "xxxx.xxxx" not found Please check your request parameters. CorrelationId: d56655ea-24fb-4dfa-97a5-a9876c0802d1
At line:1 char:1
+ Set-CsTeamsMeetingPolicy -Identity "james.bradburne" -EnrollUserOverr ...

can anyone advise me on what's going on with my command or igf there's a better way to enable voice isolation?

tia.