Venus transits the Sun, but not with every revolution.
The reason for this is that its orbital plane is at a 3 percent incline to the ecliptic, the Sun’s apparent path around Earth.
Only when Venus crosses the ecliptic at the time of its inferior conjunction will it transit the Sun.
It usually passes above or below the Sun from Earth’s point of view.
When it does cross the Sun’s surface, it appears as a small shadow.
The next time this is expected to happen is in 2012.