Set hostname - can't write to registry

[WojTec]

Delphi-Quellcode:

//  ShowMessage(BoolToStr(SetComputerName('TTX'), True));
//  ShowMessage(SysErrorMessage(GetLastError));

  // Set computer name and host name
  ShowMessage(BoolToStr(SetComputerNameEx(ComputerNamePhysicalDnsHostname, 'TTX-N'), True));

  // Set computer name
  ShowMessage(BoolToStr(SetComputerNameEx(ComputerNamePhysicalNetBIOS, 'TTX'), True));

I tried with Run as admin too.
On WXP is working, on W7 is not working.