I just called IRA. IRA said that

来源: 于 2006-03-16 15:31:38 [旧帖] [给我悄悄话] 本文已被阅读：次

in the 6th year, I should be treated as RA. I may not be able to take advantage of $5000 treaty exempt.

Since it has been already exempted from my W-2, I may need contact my former school to correct.