Deḷphi 2007, Vista and Registry read/write

Hello everybody

i'm using the code below to read/write into Windows registry. I had no
problems in delphi 7 / windows XP

now i'm porting my application in Delphi 2007 / Windows Vista

When i try to read a key in the registry (it exists for sure cause i can see
it using regedit) it's not found in my application
The code i use is:
keyvalue:=GetRVStr(hkLocalMachine,'MYCOMPANYNAME\MYAPPLICATION','MYKEY','');

The same application compiled in Delphi 7 can read the key correctly. Seems
to me that the problem is in Delphi 2007. Maybe have to change something in
the code ?

Debugging the code i see the function Registry.OpenKey(Key,false) returns
false

thank you for any help

Roberto

unit fn_Registry;

interface

uses
  Windows,
  SysUtils,
  Classes,
  Registry;

type
  TRootKeys =
(hkClassesRoot,hkCurrentConfig,hkCurrentUser,hkDynData,hkLocalMachine,hkUsers);
  EIRCannotWriteValue = class(Exception);

function RegKeyExists(Root: TRootKeys;Key: String): Boolean;

procedure WriteRVInteger(Root: Trootkeys;Key,Ident: String;Value: Integer);
procedure WriteRVStr(Root: TRootKeys;Key,Ident,Value: String);

function GetRVStr(Root: TRootKeys;Key,Ident,Default: String): String;
function GetRVInteger(Root: TRootKeys;Key,Ident: String;Default: Integer):
Integer;

implementation

procedure SetTheRoot(ARegistry: TRegistry;Root: TRootKeys);
begin
  case Root of
    hkClassesRoot: ARegistry.RootKey := HKEY_CLASSES_ROOT;
    hkCurrentUser: ARegistry.RootKey := HKEY_CURRENT_USER;
    hkLocalMachine: ARegistry.RootKey := HKEY_LOCAL_MACHINE;
    hkUsers: ARegistry.RootKey := HKEY_USERS;
    hkCurrentConfig: ARegistry.RootKey :=  HKEY_CURRENT_CONFIG;
    hkDynData: ARegistry.RootKey := HKEY_DYN_DATA;
  end;
end;

procedure WriteRVInteger(Root: Trootkeys;Key,Ident: String;Value: Integer);
var
  Registry: TRegistry;
begin
  Registry := TRegistry.Create;
  try
    SetTheRoot(Registry,Root);
    if not Registry.OpenKey(Key,TRUE) then raise
EIRCannotWriteValue.Create(Key);
    try
      Registry.WriteInteger(Ident,Value);
    except
      raise EIRCannotWriteValue.Create(Key);
    end;
  finally
    Registry.Free;
  end;
end;

procedure WriteRVStr(Root: TRootKeys;Key,Ident,Value: String);
var
  Registry: TRegistry;
begin
  Registry := TRegistry.Create;
  try
    SetTheRoot(Registry,Root);
    if not Registry.OpenKey(Key,TRUE) then
      raise EIRCannotWriteValue.Create(Format('Cannot install into registry.
Key: %s Ident: %s Value %s',[Key,Ident,Value]));
    try
      Registry.WriteString(Ident,Value);
    except
      raise EIRCannotWriteValue.Create(Format('Cannot install into registry.
Key: %s Ident: %s Value %s',[Key,Ident,Value]));
    end;
  finally
    Registry.Free;
  end;
end;

function RegKeyExists(Root: TRootKeys;Key: String): Boolean;
var
  Registry: TRegistry;
begin
  Result := False;
  Registry := TRegistry.Create;
  try
    SetTheRoot(Registry,Root);
    result:=Registry.KeyExists(Key);
  finally
    Registry.Free;
  end;
end;

function GetRVStr(Root: TRootKeys;Key,Ident,Default: String): String;
var
  Registry: TRegistry;
begin
  Result := Default;
  Registry := TRegistry.Create;
  try
    SetTheRoot(Registry,Root);
    if not Registry.KeyExists(Key) then Exit;
    if not Registry.OpenKey(Key,FALSE) then Exit;
    if not Registry.ValueExists(Ident) then Exit;
    try
      Result := Registry.ReadString(Ident);
    except
      Result := Default;
    end;
  finally
    Registry.Free;
  end;
end;

function GetRVInteger(Root: TRootKeys;Key,Ident: String;Default: Integer):
Integer;
var
  Registry: TRegistry;
begin
  Result := Default;
  Registry := TRegistry.Create;
  try
    SetTheRoot(Registry,Root);
    if not Registry.KeyExists(Key) then Exit;
    if not Registry.OpenKey(Key,FALSE) then Exit;
    if not Registry.ValueExists(Ident) then Exit;
    try
      Result := Registry.ReadInteger(Ident);
    except
      Result := Default;
    end;
  finally
    Registry.Free;
  end;
end;

end.