回复：question about EB1A: the date of recom letters

Seems that I've been forgotten. Or I didn't ask my question clearly. Made some mistakes in my previous writing as it was in midnight.
For some reasons, I didn't get to do the Eb1b, now I have to do Eb1a.
I heard that the reference letters are good when they are within half year (six months), not more than a year, I think. Is that true? Any people had the similar experience?

Thanks.