Problem in calculating number of voicemails

Hello All,

I have configured voicemail realtime and voicemail storage using unixodbc and both work fine.
Now i want to use voicemail externnotify feature to call an external script, i have specified the script in voicemail.conf but when a voicemail is left the script is not called. There is a message in the logs which states
Problem in calculating number of voicemail messages available for extension 1000.

However the message is getting stored in the voicemessage table.

Thanks in advance
Bhavi