Basically, it failed to slow down enough to go into orbit, and sailed on past.
On the other hand: "we may be able to try again when it passes by Venus six years from now", though given that the probe has a 4.5 year design life, that is a little optimistic.
It is, of course, now in a solar orbit that crosses Venus's orbit at ... I guess ... something of the order of 6 monthly intervals, so after a few orbits, it should indeed have another chance.
