The vertex coordinates of a 2D screen are usually the width and height values of the glOrtho & viewport parameters.
As you have not done that and rolled your own (which I don’t understand) you need to check if these are the correct coordinates. Remeber, these coordinates will be transformed by the ModelView and Projection matricies, so the values you use here are very much linked to the projection matrix you setup earlier.
and if you have done this, do you have a mipmap complete texture? ie. all texture levels populated, or mipmaps disabled - see Common Mistakes - OpenGL Wiki
sure i have glEnable(GL_TEXTURE_2D); and any line with mipmap which means disabled i think. i use texture to display framebuffer as i pointed before. is it the best way to do that ?
You can also use [b]glBlitFramebuffer[/b] to perform the copy. It’s more convenient and you can skip that deprecated immediate mode full screen quad drawing code.