Sms dongle incoming config

Hi everybody…
the following are the dongle incoming context for sms receiving by mail of two asterisk boxes…
the first is the old one…function properly since 2013
using the same config in a second box didn’t function at all…system call couldn’t write to file
I have to modify the config as shown above…i have to use " instead of '
is there any reason?

[dongle_incoming]
exten => sms,1,Noop(Incoming SMS from ${CALLERID(num)} ${BASE64_DECODE(${SMS_BASE64})})
exten => sms,n,System(echo ‘${STRFTIME(${EPOCH},%Y-%m-%d %H:%M:%S)} - ${DONGLENAME} - ${CALLERID(num)}: ${BASE64_DECODE(${SMS_BASE64})}’ >> /var/log/asterisk/sms.txt)
exten => sms,n,System(mail -s ${CALLERID(num)} xxxx@xxxxx.it < /var/log/asterisk/sms.txt)
exten => sms,n,System(rm -f /var/log/asterisk/sms.txt)
exten => sms,n,Hangup()

[dongle_incoming]
exten => sms,1,Noop(Incoming SMS from ${CALLERID(num)} ${BASE64_DECODE(${SMS_BASE64})})
exten => sms,n,System(echo “${STRFTIME(${EPOCH},%Y-%m-%d %H:%M:%S)} - ${DONGLENAME} - ${CALLERID(num)}: ${BASE64_DECODE(${SMS_BASE64})}” >> /var/log/asterisk/sms.txt)
exten => sms,n,System(mail -s ${CALLERID(num)} xxx@xxxxx.it < /var/log/asterisk/sms.txt)
exten => sms,n,System(rm -f /var/log/asterisk/sms.txt)
exten => sms,n,Hangup()