how can I test get-wmiobject

Hello,

How can I modify this code for testing a wmi query without having the following error :
Get-WmiObject : Invalid namespace
At line:3 char:23
+ $cluster=get-wmiobject <<<<  -class "MSCluster_Cluster" -namespace "root\mscluster" -computername "$mach_name" | select -ExpandProperty Name
    + CategoryInfo          : InvalidOperation: (:) [Get-WmiObject], ManagementException
    + FullyQualifiedErrorId : GetWMIManagementException,Microsoft.PowerShell.Commands.GetWmiObjectCommand

The query :

try
{
$cluster=get-wmiobject -class "MSCluster_Cluster" -namespace "root\mscluster" -computername "$mach_name" | select -ExpandProperty Name    
}
catch [Exception]
{ 
    echo "$cluster" | out-file $LOG_FILE -ErrorVariable ERR1 -encoding "default" -append -ErrorAction silentlycontinue 
}

Thanks
bibi