Почему не меняется текст в заголовке окна?

#include <windows.h>
#include <string>
#include <time.h>
 
LRESULT CALLBACK WindowProcess(HWND, UINT, WPARAM, LPARAM);
 
const std::string& generateRandomString();
std::string GetLastErrorAsString();
 
const INT TITLE_SIZE = 20;
 
 
CCHAR calculatorClassName[] = "ApplicationFrameInputSinkWindow";
//CCHAR calculatorClassName[] = "ApplicationFrameWindow";
//CCHAR calculatorClassName[] = "Notepad";
 
 
INT WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrevInst, LPSTR pCommandLine, int nCommandShow)
{
    srand(time(0));
 
    TCHAR className[] = L"ChangeCalculatorTitleClass";
    HWND hWindow;
    MSG message;
    WNDCLASSEX windowClass;
 
    windowClass.cbSize = sizeof(windowClass);
    windowClass.style = CS_HREDRAW | CS_VREDRAW;
    windowClass.lpfnWndProc = WindowProcess;
    windowClass.lpszMenuName = NULL;
    windowClass.lpszClassName = className;
    windowClass.cbWndExtra = NULL;
    windowClass.cbClsExtra = NULL;
    windowClass.hIcon = LoadIcon(NULL, IDI_WINLOGO);
    windowClass.hIconSm = LoadIcon(NULL, IDI_WINLOGO);
    windowClass.hCursor = LoadCursor(NULL, IDC_ARROW);
    windowClass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
    windowClass.hInstance = hInst;
 
    if (!RegisterClassEx(&windowClass))
    {
        MessageBox(NULL, L"Failed to register the class!", L"Error", MB_OK | MB_ICONERROR);
        return NULL;
    }
    hWindow = CreateWindow(className,
        L"Program counting the number of mouse clicks",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT,
        NULL,
        CW_USEDEFAULT,
        NULL,
        (HWND)NULL,
        NULL,
        HINSTANCE(hInst),
        NULL
    );
    if (!hWindow) {
        MessageBox(NULL, TEXT("Failed to create the window!"), TEXT("Error"), MB_OK | MB_ICONERROR);
        return NULL;
    }
    ShowWindow(hWindow, nCommandShow);
    UpdateWindow(hWindow);
    while (GetMessage(&message, NULL, NULL, NULL)) {
        TranslateMessage(&message);
        DispatchMessage(&message);
    }
    return message.wParam;
}
 
LRESULT CALLBACK WindowProcess(HWND hWindow, UINT uMessage, WPARAM wParameter, LPARAM lParameter)
{
    static TCHAR text[100];
    static HBRUSH brush = CreateSolidBrush(RGB(144, 164, 174));
 
    switch (uMessage)
    {
    case WM_CREATE:
        SetClassLongPtr(hWindow, GCLP_HBRBACKGROUND, (LONG)brush);
        break;
 
    case WM_LBUTTONDOWN:
    {
        //HWND hCalc = FindWindow(LPCWSTR(calculatorClassName), TEXT("Калькулятор"));
        //HWND hCalc = FindWindow(TEXT("ApplicationFrameWindow"), NULL);
        HWND hCalc = ::FindWindowEx(0, 0, TEXT("ApplicationFrameWindow") /*LPCWSTR(calculatorClassName)*/, TEXT("Калькулятор"));
        if (!hCalc)
            MessageBox(hWindow, /*LPCWSTR(GetLastErrorAsString().c_str())*/ TEXT("You must open "Calculator""), TEXT("Error"), MB_OK | MB_ICONSTOP);
        else
            SetWindowText(hCalc, LPCWSTR(generateRandomString().c_str()));
    }
        break;
 
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWindow, uMessage, wParameter, lParameter);
    }
    return NULL;
}
 
const std::string& generateRandomString()
{
    static const char alphanum[] =
        "0123456789"
        "!@#$%^&*"
        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        "abcdefghijklmnopqrstuvwxyz";
    static int stringLength = sizeof(alphanum) - 1;
 
    std::string rand_str;
 
    for (INT i = 0; i < TITLE_SIZE; i++)
        rand_str += alphanum[rand() % stringLength];
 
    return rand_str;
}
 
std::string GetLastErrorAsString()
{
    DWORD errorMessageID = ::GetLastError();
    if (errorMessageID == 0)
        return std::string();
 
    LPSTR messageBuffer = nullptr;
    size_t size = FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
        NULL, errorMessageID, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPSTR)&messageBuffer, 0, NULL);
 
    std::string message(messageBuffer, size);
 
    LocalFree(messageBuffer);
 
    return message;
}

CCHAR calculatorClassName[] = ...
FindWindowEx (  ... , LPCWSTR(calculatorClassName), ... )   //  Ошибка !  Не следует использовать приведение типа

SetWindowText(hCalc, TEXT("New title") );
// SetWindowText(hCalc, LPCWSTR(generateRandomString().c_str()));   // та же ошибка, см. учебник, что такое приведение типа (именно в случае указателя ! )