Results on hard diffraction from CDF are reviewed and compared with
predictions based on the diffractive structure function of the proton measured
in deep inelastic scattering at HERA.  The predictions are generally larger
than the measured rates by a factor of approximately 6, suggesting a breakdown
of conventional factorization.  Correct predictions are obtained by scaling
the rapidity gap probability distribution of the diffractive structure
function to the total integrated gap probability.  The scaling of the gap
probability is traced back to the pomeron fux renormalization hypothesis,
which was introduced to unitarize the soft diffraction amplitude.