some difficult

I’ve some difficult to setting update email to customer who open a case… I’ve made a workflow, but seems it don’t work. What’s the way? Thank you

and the email reply when customer open a new case is always:
We’ve received your case $acase_name (# $acase_case_number) on $acase_date_entered
Status$acase_status
Reference$acase_case_number
Description$acase_description
instead the obliect is right: Re: [CASE:10]