shell编程新手错误请教

晚上刚刚编写了一个shell 但是不知为什执行的时候总是有错误
#!/bin/bash
#program:
# This program will show the user's choice
#History:
# 2013/1/16 nck first release
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:/usr/local/sbin:~/bin
export PATH
read -p "please input (Y/n):" yn
if [ "$yn" == "Y" ] || [ "$yn" == "y" ]; then
echo "OK ,continue "
elif [ "$yn" == "N" ] || [ "$yn" == "n" ]; then
echo "OK , interrupt ! "
else
echo " I don't konw whit is your choise "
fi
完成后总是出现如下错误i
unexpected operator
检查了几遍都没有找到错误处 请教路过的高手指教