glReadPixels doesn't do GL_LUMINANCE_INTEGER_EXT

I have a LUMINANCE16I_EXT texture connected to the current framebuffer socket GL_COLOR_ATTACHMENT0_EXT.
I make this socket readbuffer with a glReadBuffer call.

When trying to do a glReadPixels call using GL_LUMINANCE_INTEGER_EXT and GL_SHORT, OpenGL throws an Invalid Operation error?