blit fbo that has multiple textures bound


with glBlitFramebuffer it’s possible to copy the content from one buffer to another buffer. The short description and code at about that features doesnt mention how to handle
if the framebuffer objects have multiple targets. There are 4
textures bound to my fbo. I tried to blit but I see only a black screen. So I set glReadBuffer(GL_COLOR_ATTACHMENT2) right after
glBindFramebuffer(GL_READ_FRAMEBUFFER,…). But it didnt work either.

What did I wrong ?