Thread: ChangeDisplaySettings - Blank?

I have a very small section of code that is confusing me, and seems to be causing a blackscreen. The codey goes something like this:

Code:

        DEVMODE dm = { 0 };
        LONG ret = 0; DWORD i = 0;
        

        dm.dmSize = sizeof(DEVMODE);
        dm.dmDriverExtra = 0;

        while( ::EnumDisplaySettings( 0, i, &dm ) )
        {
            if(dm.dmPelsHeight == 600 &&
                dm.dmPelsWidth == 800 &&
                dm.dmBitsPerPel == 32)
            {
                ret = 1;
                break;
            }
            i++;
        }

        if(ret)
        {
            dm.dmFields = DM_PELSWIDTH | DM_PELSHEIGHT | DM_BITSPERPEL;
            ret = ::ChangeDisplaySettings( &dm, CDS_FULLSCREEN );
            if( ret != DISP_CHANGE_SUCCESSFUL ) // Blarhgfadgigafdg.
        }

When my current screen resolution in 800 x 600, and it is changing into fullscreen that way, this works, and I get stuff to show on the screen. However, when it is not, it says DISPLAY_CHANGE_SUCCESSFUL but of course I can not see anything being rendered. Is there a better way I should approach this?