wglcreatecontext c# unwell nonetheless managed c++

i'm perplexing opengl c#. i have following formula fails blunder 2000 error_invalid_pixel_format

first definitions:

[dllimport("user32.dll", charset = charset.auto, setlasterror = true, exactspelling = true)]
public stationary extern intptr getdc(intptr hwnd);

[structlayout(layoutkind.sequential)]
    open struct pixelformatdescriptor
    {
        open vacant init()
        {
            nsize = (ushort) marshal.sizeof(typeof (pixelformatdescriptor));
            nversion = 1;
            dwflags = pfd_flags.pfd_draw_to_window | pfd_flags.pfd_support_opengl | pfd_flags.pfd_doublebuffer | pfd_flags.pfd_support_composition;
            ipixeltype = pfd_pixel_type.pfd_type_rgba;
            ccolorbits = 24;
            credbits = credshift = cgreenbits = cgreenshift = cbluebits = cblueshift = 0;
            calphabits = calphashift = 0;
            caccumbits = caccumredbits = caccumgreenbits = caccumbluebits = caccumalphabits = 0;
            cdepthbits = 32;
            cstencilbits = cauxbuffers = 0;
            ilayertype = pfd_layer_types.pfd_main_plane;
            breserved = 0;
            dwlayermask = dwvisiblemask = dwdamagemask = 0;
        }
        ushort nsize;
        ushort nversion;
        pfd_flags dwflags;
        pfd_pixel_type ipixeltype;
        byte ccolorbits;
        byte credbits;
        byte credshift;
        byte cgreenbits;
        byte cgreenshift;
        byte cbluebits;
        byte cblueshift;
        byte calphabits;
        byte calphashift;
        byte caccumbits;
        byte caccumredbits;
        byte caccumgreenbits;
        byte caccumbluebits;
        byte caccumalphabits;
        byte cdepthbits;
        byte cstencilbits;
        byte cauxbuffers;
        pfd_layer_types ilayertype;
        byte breserved;
        uint dwlayermask;
        uint dwvisiblemask;
        uint dwdamagemask;
    }

    [flags]
    open enum pfd_flags : uint 
    {
        pfd_doublebuffer = 0x00000001,
        pfd_stereo = 0x00000002,
        pfd_draw_to_window = 0x00000004,
        pfd_draw_to_bitmap = 0x00000008,
        pfd_support_gdi = 0x00000010,
        pfd_support_opengl = 0x00000020,
        pfd_generic_format = 0x00000040,
        pfd_need_palette = 0x00000080,
        pfd_need_system_palette = 0x00000100,
        pfd_swap_exchange = 0x00000200,
        pfd_swap_copy = 0x00000400,
        pfd_swap_layer_buffers = 0x00000800,
        pfd_generic_accelerated = 0x00001000,
        pfd_support_directdraw = 0x00002000,
        pfd_direct3d_accelerated = 0x00004000,
        pfd_support_composition = 0x00008000,
        pfd_depth_dontcare = 0x20000000,
        pfd_doublebuffer_dontcare = 0x40000000,
        pfd_stereo_dontcare = 0x80000000
    }

    open enum pfd_layer_types : byte
    {
        pfd_main_plane = 0,
        pfd_overlay_plane = 1,
        pfd_underlay_plane = 255
    }

    open enum pfd_pixel_type : byte
    {
        pfd_type_rgba = 0,
        pfd_type_colorindex = 1
    }

    [dllimport("gdi32.dll", charset = charset.auto, setlasterror = true, exactspelling = true)]
    open stationary extern int choosepixelformat(intptr hdc, [in] ref pixelformatdescriptor ppfd);

    [dllimport("gdi32.dll", charset = charset.auto, setlasterror = true, exactspelling = true)]
    open stationary extern bool setpixelformat(intptr hdc, int ipixelformat, ref pixelformatdescriptor ppfd);
[dllimport("opengl32.dll", charset = charset.auto, setlasterror = true, exactspelling = true)]
    open stationary extern intptr wglcreatecontext(intptr hdc);

and formula fails:

intptr dc = win.getdc(hwnd);

var pixelformatdescriptor = new gl.pixelformatdescriptor();
pixelformatdescriptor.init();

var pixelformat = gl.choosepixelformat(dc, ref pixelformatdescriptor);
if(!gl.setpixelformat(dc, pixelformat, ref pixelformatdescriptor))
    pitch new win32exception(marshal.getlastwin32error());
intptr hglrc;
if((hglrc = gl.wglcreatecontext(dc)) == intptr.zero)
    pitch new win32exception(marshal.getlastwin32error()); //<----- here i have exception

the same formula managed c++ working

hdc dc = getdc(hwnd);

pixelformatdescriptor pf;
pf.nsize = sizeof(pixelformatdescriptor);
pf.nversion = 1;
pf.dwflags = pfd_draw_to_window | pfd_support_opengl | pfd_doublebuffer | pfd_support_composition;
pf.ccolorbits = 24;
pf.credbits = pf.credshift = pf.cgreenbits = pf.cgreenshift = pf.cbluebits = pf.cblueshift = 0;
pf.calphabits = pf.calphashift = 0;
pf.caccumbits = pf.caccumredbits = pf.caccumgreenbits = pf.caccumbluebits = pf.caccumalphabits = 0;
pf.cdepthbits = 32;
pf.cstencilbits = pf.cauxbuffers = 0;
pf.ilayertype = pfd_main_plane;
pf.breserved = 0;
pf.dwlayermask = pf.dwvisiblemask = pf.dwdamagemask = 0;

int ipf = choosepixelformat(dc, &pf);
setpixelformat(dc, ipf, &pf);

hglrc hglrc = wglcreatecontext(dc);

i've attempted perspective 64-bit ati distinguished tag windows xp 32-bit nvidia same outcome both cases.

also i wish plead i don't wish any already combined horizon it.



can anyone arrangement me where bug c# formula causing exception?