What was wrong with my code ??? it look right to me but it give me the error

datetime="`echo $3 | nawk '{n=split($1, da, "/"); print da[2]"/" da[3]"/20" da[1] " " $2}'`";


this is the error `(' is not expected.

if datetime is work then I solve my problem .

I test this and it works ???
echo '06/02/25 12:05:06' | nawk '{n=split($1, da, "/"); print da[2]"/" da[3]"/20" da[1] " " $2}'

Please knock me where i made mistake .
Thanks,