i can't edit a key with RegSetValue

the next code is write by me, first read the size of the string ,then take the string, edit the string and try to modify the keywith RegSetValue, but never change and not return error the function RegSetValue.
What am I doing wrong?

Code:

int environmentValueAdd(wchar_t* pathToAdd){
	HKEY root=HKEY_LOCAL_MACHINE;
	wchar_t directorio[]=L"SYSTEM\\CurrentControlSet\\Control\\Session Manager\\Environment";
	//wchar_t Path[]=L"Path";
	wchar_t Path[]=L"Pate";//---copy of the real path to not break the real.
	unsigned long tipoValue= REG_EXPAND_SZ;
	HKEY environment;
	unsigned long size=1;//asigno un valor no nulo
	//i can't use RegGetValue becouse minimus OS is XP 64bits or vista
	long returnStatus =RegOpenKeyEx(root,directorio,0,KEY_ALL_ACCESS, &environment);
	if (returnStatus != ERROR_SUCCESS){
		return 1;
	}
	returnStatus=RegQueryValueEx(environment , Path , NULL, &tipoValue ,NULL,(LPDWORD)&size);
	//pone en size el tamaño del dato en bytes
	if (returnStatus != ERROR_SUCCESS){
		RegCloseKey(environment);
		return 2;
	}
	wchar_t* data=(wchar_t*)malloc((unsigned int)size);
	if(!data)return 5;
	returnStatus =RegQueryValueEx(environment , Path , NULL, &tipoValue ,(LPBYTE)data,(LPDWORD)&size);//datos...
	if (returnStatus != ERROR_SUCCESS){
		RegCloseKey(environment);
		free(data);
		return 3;
	}
	
	MessageBox(NULL,data,L"REG_EXPAND_SZ",MB_OK);
	
	wchar_t* remplaced=(wchar_t *)malloc((wcslen(data)+ wcslen(pathToAdd) + 3) * sizeof(wchar_t));//uno demas
	if(!remplaced)return 6;
	wcscpy(remplaced,data);
	wcscat(remplaced,L";");
	wcscat(remplaced,pathToAdd);
	size=(wcslen(remplaced) + 1) * sizeof(wchar_t);

	returnStatus =RegSetValueEx(environment,Path,0,tipoValue,(LPBYTE)data,size);
	if (returnStatus != ERROR_SUCCESS){
		RegCloseKey(environment);
		free(data);
		return 4;
	}
	RegFlushKey(environment);

	SendMessageTimeoutA(HWND_BROADCAST, WM_SETTINGCHANGE, 0,
    (LPARAM) "Environment", SMTO_ABORTIFHUNG,
    5000,(PDWORD_PTR)&returnStatus);

	free(data);

	returnStatus=RegQueryValueEx(environment , Path , NULL, &tipoValue ,NULL,(LPDWORD)&size);
	//pone en size el tamaño del dato en bytes
	if (returnStatus != ERROR_SUCCESS){
		RegCloseKey(environment);
		return 2;
	}
	data=(wchar_t*)malloc((unsigned int)size);
	if(!data)return 5;
	returnStatus =RegQueryValueEx(environment , Path , NULL, &tipoValue ,(LPBYTE)data,(LPDWORD)&size);//datos...
	if (returnStatus != ERROR_SUCCESS){
		RegCloseKey(environment);
		free(data);
		return 3;
	}
	MessageBox(NULL,data,L"REG_EXPAND_SZ",MB_OK);

	RegCloseKey(environment);
	free(data);
	free(remplaced);
	return 0;//exito
}

thanks

This code is not very correct.
See MSDN samples (KB, SDK, doc) or on WIN32 ng for more advanced code
(and you set data instead of environment...)

thanks Alex31.
yesterday at 24:30 discoverred this error.
i so stupid.
now the code works!!