Depreciation?????

Hello firendzz here is one querry relates to dep

block value on 01.04.2009 rs.100000

additions made before 30.09 are rs.500000 on mew machinery eligible for additional dep

one out of block sold in dec for rs.500000(not purchased one as it is but from block)

now closing block value rs.100000 left  and we will charge additional ep on which value  i.e. at 500000 @ 20%  and if yes then will i sustain loss of normal dep as aftr additnl dep block will be nil????

plz clarify in this regard 

thnxx