/bin/sh and /bin/ksh problem

we have a shell script that we are using in KSH

if [[ "${oraserver}" = @(+ASM*) ]]; then
                _IFS=$IFS
                IFS=:

and it's failing on /bin/sh . Is there a simple way to modify it to work on both . ( not with awk)

Thanks in adv

try a single [ after if

 
if [ "${oraserver}" = @(+ASM*) ]

case $oraserver in
  +ASM* ) _IFS=$IFS IFS=:;;
esac  

Thankyou Guys .