请教在custom.php 中使用$ci->dip->address($t['inputip']) 提示错误

php 95 ---->

ERROR - 2020-08-08 18:33:12 --> Severity: error --> Exception: Call to a member function address() on null D:\wwwroot\config\custom.php 95 ----> 

function vg_excel_ip($cid,$kw='陕西',$pagesize=5000,$page=1) {

  $ci = &get_instance();

 // sql 省略

 foreach ($list as $t) {

  $ipaddress = $ci->dip->address($t['inputip']);

   //省略

}