Case ID pulling through as blank on auto-response email

Hello!

Can’t seem to get this to work when a customer sends in an email it comes through like this;

[i]We’ve received your case Test Ticket 25 (# ) on 2017-05-18 14:37:01

Status New
Reference
Description wqrrthjtrytjdg[/i]

Even Though it’s setup like this;

Hi $contact_first_name $contact_last_name,

We’ve received your case $acase_name (# $acase_case_number) on $acase_date_entered

Status $acase_status
Reference $acase_case_number
Description $acase_description