background check!

[gini22us]

hello everybody,
i have a couple questions,
i'm almost graduating college,and i was thinking to apply with dept of agriculture for a job ,however i don't know what to do about 1 question have you ever been arrested?
6 years ago i was arrested for a misdemeanor,and the case was dismissed , no conviction.the case was expunged.i received back fingerprints,mugshots,even the original arrest report.
i did a background check on me and nothing,i even requested the FBI identification record under FOIA
http://www.fbi.gov/hq/cjisd/fprequest.htm
and it came back with a big stamp No arrest record.
i have a friend in police and did a NCIC III query for me and i saw with my own eyes No idetifiable recordin III for ...
i also checked the state police and same thing.
i don't think FBI will lie by sending me one answer and provide the Dept of agriculture another,right?
they are required to provide me with teh rap sheet if any,correct?
i think my fingerprints were never sent to FBI in first place,and evidently there is no arrest record.
under FOIA request for rapsheet done through IAFIS, is the same background done as applying for license, naturalization,military emplyoment,federal employmeny,right or not?
hope to hear from you.