missing invoice number in csv file

Have a problem that the csv export doesn't have the invoice number in it.
I can't see there is an option to include or not include this so assume it should be included by default.
All the custom fields are included.
thanks

Hi Shope

We don't have invoice number included in the export by default. If you want it in the CSV export, please submit a support ticket sending us admin and FTP account of your site so that we can modify code for you to add support for the feature !

Regards,

Tuan