Asterisk voicemail grettings automatic deletion

I configured voicemail on astresik and all was going perfectly
I use a custom grettings sound stored aside INBOX folder .
-INBOX path :/var/www/html/voicemail/xxxxxxxx/INBOX
-Voicemail grettings path : /var/www/html/voicemail/xxxxxxxx/unvail.ulaw
After installing odbc connector to store voicemail recordings in database i meet this problem :
When i call a number and i leave a voice mail ,the voicemail gretting sound is deleted automaticlly .
Thanks to help me resolve the problem.

#uname -a
Linux voip.xxxxx 2.6.32-696.3.1.el6.x86_64 x86_64 x86_64 x86_64 GNU/Linux

asterisk -rx ‘core show version’

Asterisk certified/11.6-cert16 built by root @ voip.xxxxxxx on a x86_64

-CentOS release 6.9

You need to store the greeting in the database, Realtime creates the greeting that is played from the blob in the database when you call the box.