CreateWindowsEx fails when creating window - c++

Question

I am new to win32 API GUI programming in C++. When the program is compiled and executed, It always fails at CreateWindowsEx. Sorry but this only what I can explain at this moment.
Aside from that, It passes the window registration, which is good. But from the time Windows Creation executed, it always return NULL.
Here's my C++ code:
#include <windows.h>
LRESULT CALLBACK WindowProcedure(HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrevInst, LPSTR args, int ncmdshow){
//MessageBox(NULL, "Hello ", " H", MB_OK);
WNDCLASSEX wc = {0};
//memset(&wc,0,sizeof(wc));
//wc.cbSize = sizeof(WNDCLASSEX);
memset(&wc,0,sizeof(wc));
wc.cbSize = sizeof(WNDCLASSEX);
wc.lpfnWndProc = WindowProcedure; /* This is where we will send messages to */
wc.hInstance = hInst;
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
/* White, COLOR_WINDOW is just a #define for a system color, try Ctrl+Clicking it */
wc.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
wc.lpszClassName = "WindowClass";
wc.hIcon = LoadIcon(NULL, IDI_APPLICATION); /* Load a standard icon */
wc.hIconSm = LoadIcon(NULL, IDI_APPLICATION); /* use the name "A" to use the project icon */
if(! RegisterClassEx(&wc) ){
MessageBox(NULL, "Error 1", " H", MB_OK);
return -1;
}
HWND hwnd = CreateWindowEx(WS_EX_CLIENTEDGE,"WindowClass","Caption",WS_VISIBLE|WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, /* x */
CW_USEDEFAULT, /* y */
640, /* width */
480, /* height */
NULL,NULL,hInst,NULL);
//returns 0x0
//return GetLastError();
if( hwnd == NULL){
MessageBox(NULL, "Error 2", " H", MB_OK);
return GetLastError();
}
MSG msg = {0};
while( GetMessage(&msg, NULL, 0, 0) ){
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}
LRESULT CALLBACK WindowProcedure(HWND hWnd, UINT msg, WPARAM wp, LPARAM lp){
switch(msg){
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProcW(hWnd, msg, wp, lp);
}
return 0;
}
Please approach in the level of a novice, so it easy for me to understand what should be done.

Answer 1

The reason why the CreatewindowEx fails is because of DefWindowProcW should be DefWindowProc.
DefwindowProcW is used with CreateWindowW, but since it is using CreateWindowEx, DefWindowProc should be the correct one to use.