   Problem with glMapBufferARB
  Hello everybody,I'm trying to build a complete software implementation of a videodecoder, so and using one triangle and 1 texture that gets updated every frame (yeah not best solution)But i get error in next linestypedef unsigned int TColor;TColor make_color(float r, float g, float b, float a){    return   ((int)(a) << 24) |   ((int)(b) << 16) |   ((int)(g) <<  8) |   ((int)(r) <<  0);}TColor*d_dst = NULL;is defined in beginning..glutInit(&argc,argv);glutInitDisplayMode(GLUT_RGBA | GLUT_SINGLE);glutInitWindowSize(g_width,g_height);printf("..Loading extensions: %s\n", glewGetErrorString(glewInit()));if(!glewIsSupported("GL_VERSION_2_0 ""GL_ARB_pixel_buffer_object ""GL_EXT_framebuffer_object ")){fprintf(stderr, "ERROR: Support for necessary OpenGL extensions missing.");fflush(stderr);}glEnable(GL_TEXTURE_2D);glGenTextures(1, &gl_Tex);glBindTexture(GL_TEXTURE_2D, gl_Tex);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, g_width, g_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, h_Src);glGenBuffers(1, &gl_PBO);glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, gl_PBO);glBufferData(GL_PIXEL_UNPACK_BUFFER_ARB, g_width * g_height * 4, h_Src, GL_STREAM_COPY);is in initand in my displayfuncd_dst = (TColor*)glMapBufferARB(gl_PBO, GL_READ_WRITE);//some calculations on which i have to write to the texture, buffer, ..d_dst[Cposition++] = make_color(r,g,b,0);which complains with a Access violation writing location 0x00000000 . .Anybody would be so kind to look through this code and help me (and explain what i did wrong so I will never do it again ;) )..Kind regardsEDIT * TYPO   
What you need to know about debugging.Your problem is not (directly) an OpenGL error. You're simply trying to read or write from a null pointer. Use a debugger to find out where that pointer is, and then find out why it is null.   ;  Looks like you forgot to create a window.Here is an exampleglutInit(&argc, argv);glutInitWindowPosition(10, 10);glutInitWindowSize(512, 512);glutInitDisplayMode(GLUT_DOUBLE | GLUT_DEPTH | GLUT_RGBA );glutCreateWindow("title");