It won't solve your problem per-se, but you should be checking for error(s) from Win32::OLE->GetObject e.g. (extract from Win32 Perl Scripting The Administrators Handbook - Roth)

$wmi = Win32::OLE->GetObject($class) ||
   die "Cannot connect to machine: $class - " . Win32::OLE->LastError(
+);
[download]

You are sure that the remote machine has WinMgmts.exe installed - if not, it won't support WMI.