reply/forward not recorded at SD

Hi,

recently we upgrade from SD 6 to SD 7 and found below issues.

when we reply to a request, it will not be recorded/listed in the SD for future reference. But the mail was delivered to users.

my observation was, when i choose to reply from the user communication, this reply will be assigned to that communication ticket no. and will not be listed.

for eg :
User reported an incident. Ticket No. 1200

Service Desk reply to this requester.

Requester reply back, merged to ticket 1200, but the coomunication no. may be 1205

when i choose to reply to this communication 1205, i can reply and it is linsted under 1205 and not 1200

So, when i try to view my communications, i cannot find

Appreciate any advice on above.

thank you.