powershell get-service -computername

I am using a powershell script to check if all necessary services in a 9 server cluser are running. 

get-service ServiceName* -ComputerName Server1, Server2, ... Server9  ## with WINS names or 

get-service ServiceName* -ComputerName Server1.FQDN, Server2.FQDN, ... Server9.FQDN  ## with FQDN names

the result is that I get the status of 5 servers and 4 servers don't respond

if I use get-service ServiceName* -ComputerName ServerX that does not repond in the server list above, it will reply 

How can I make sure, that when I query 9 Servers all 9 will respond? 

Siegmund Sonntag