CreateCompatibleBitmap doesn´t work

Hallo!
I have the following problem. I want to move the "clientArea" of a program with another program. I have the following code.

Code:

---

...
        RECT mRect;
       
        HWND hwnd = FindWindow( NULL, "Flash" );
        ::GetClientRect( hwnd, &mRect );
       
        HDC hdc_desktop        = ::GetDC( hwnd );
        HDC hdcMem                = ::CreateCompatibleDC( hdc_desktop );

        HBITMAP bmp                = ::CreateCompatibleBitmap( hdc_desktop, mRect.right, mRect.bottom);
        ::SelectObject( hdcMem, bmp);
       
        ::SetTextColor( hdcMem, COLORREF( 0xFFFFFF ) );
        ::SetBkColor( hdcMem, COLORREF(0xFFFF00));

        ::TextOut( hdcMem, 0, 0, "Hallo windows", 13 );
        BitBlt( hdc_desktop, 0, 0, mRect.right, mRect.bottom, hdcMem, 0, 0, SRCCOPY );
...

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But this doesn´t work. The bitmap i get with createCompatibleBitmap and that i am blitting to the window seems to be a black bitmap. Where is my mistake? The text i am writing to the bitmap is correct!

Thanks