CommandArgumet Error

public void  PagerButtonClick(object sender, EventArgs e)
   {
      string arg = e.CommandArgument.ToString();
       //string arg = sender.ToString();
       switch (arg)
       {
           case "next":
               //The next Button was Clicked
               if ((dgcategory.CurrentPageIndex < (dgcategory.PageCount - 1)))
               {
                   dgcategory.CurrentPageIndex += 1;
               }

               break;
           case "prev":
               //The prev button was clicked
               if ((dgcategory.CurrentPageIndex > 0))
               {
                   dgcategory.CurrentPageIndex -= 1;
               }

               break;
           case "last":
               //The Last Page button was clicked
               dgcategory.CurrentPageIndex = (dgcategory.PageCount - 1);
               break;
           default:
               //The First Page button was clicked
               dgcategory.CurrentPageIndex = Convert.ToInt32(arg);
               break;
       }
       //selpagecombo()
       //Now, bind the data!
       BindCategory();
   }

'System.EventArgs' does not contain a definition for 'CommandArgument' and no extension method 'CommandArgument' accepting a first argument of type 'System.EventArgs' could be found (are you missing a using directive or an assembly reference?)