Set hostname - can't write to registry

[WojTec]

I'm trying change host name (like My Computer properties --> Computer Name).

I did this:

Delphi-Quellcode:

if OpenKey('SYSTEM\CurrentControlSet\services\Tcpip\Parameters', True) then
try
  WriteString('NV Hostname', FHostName);
  WriteString('Hostname', FHostName);
finally
  CloseKey;
end;

but raises exception that failed to set data for these values.

So, I tried this:

Delphi-Quellcode:

function SetComputerNameEx(NameType: TComputerNameFormat; lpComputerName: PWideChar): BOOL; stdcall;
  external 'kernel32.dll' name 'SetComputerNameExW';

SetComputerNameEx(ComputerNamePhysicalDnsHostname, 'NewName');

Returns false. I'm administrator.