powershell sql server performance

Hi,

    I am trying to get performance data using powershell. When I run the command "get-wmiobject -list" I get classes like

Win32_PerfRawData_MSSQLSQLEXPRESS1_MSSQLSQLEXPRESS1Locks. However when I run the command

get-wmiobject -query "select * from Win32_PerfRawData_MSSQLSQLEXPRESS1_MSSQLSQLEXPRESS1Locks" powershell gives me an error. Why is this happening? any help in this regard is appreciated.

Regards

Sourashis