copying texture to system framebuffer


im trying to use a FBO, but this time instead of renderbuffer objects i want to use textures
i dont get any errors on creation of the framebuffer (using glCheckFramebufferStatus(…)), so i assume there is no error
but when i try to copy the data from the framebuffer (using glBlitFramebuffer(…)), opengl reports an error: GL_INVALID_FRAMEBUFFER_OPERATION

how can i copy the data from a texture into the default framebuffer ?
or do i have to render a simple quad with that texture ?

nevermind, i actually overlooked anothe error message, framebuffer wasnt initialized correctly …