Not sure what your ranking is, but here are the division restrictions based on the PAPA website:
http://papa.org/competitions/papa-world-championships/papa-20-world-championships/
Players ranked between 1 and 199 in the World Pinball Player Rankings are restricted to Division A.
Players ranked between 200 and 599 in the World Pinball Player Rankings are restricted to Division B or higher.
Only unranked players, or players ranked higher than 7500 in the World Pinball Player Rankings are permitted to compete in Division D.