Category change worrys

[ravpatel]

hello guys
i have question related about category ..
my parents filled a petition file for me on Apr 2007 and my category F2A,, i got approval latter and BMB number letter too under 21 unmarried .. so before few days i sent a email to NVC and ask them regrading my file status so they reply me and said ..your category has changed from F2a to F2B ..so my question how can they changed my category ?? and so now what i have to do ?
Thank you all

[immihelp]

That means you just turned 21 years of age.

[ravpatel]

no ..right now i m 23 years ..but when my parents filled file at that time i was under 21 ,,

[harry_champ]

hey.. i think during the processing time your category is changed..!!

[ravpatel]

no brother ,,,
..one of my frnd ,,he has same petition file as mine ...his parents are in usa ..they put the file for him like mine..his prority date in 2006 n mine 1 is 2007 ...but we are on same category ..F2A ..he got green card before 3 month...and he is also over 21 age ..we were a classmate .so we are on same age ....