You refer to this https://erpnext.org/docs/user/manual/en/setting-up/settings/naming-series
Perhaps you must run as Administrator and/or be in developer_mode Naming series for new doc type - #18 by priya_s
You refer to this https://erpnext.org/docs/user/manual/en/setting-up/settings/naming-series
Perhaps you must run as Administrator and/or be in developer_mode Naming series for new doc type - #18 by priya_s