shell - problem in scripting -

when executing on command line:

awk 'begin{ofs=fs=","}$3~/^353/{print}' axem10_20110510100219_59.dat_353 >log 

it executes vey nicely without taking time , instantly gives me output file.

but when including in shell script :

#!/usr/bin/ksh  in *.dat_353 awk 'begin{ofs=fs=","}$3~/^353/{print}'  ${i} > ${i}_changed >/dev/null done  exit 

the script generating 0 byte files. may know problem here?

remove >/dev/null because stdout being redirected to.