gridview更新数据时出现未将对象引用设置到对象的实例问题

源错误:

行 89: {
行 90: //pet.ID = Convert.ToInt16((GridView1.Rows[e.RowIndex].FindControl("Label1")as Label).Text);

行 91: pet.Kind = (GridView1.Rows[e.RowIndex].FindControl("TextBox2") as TextBox).Text;
行 92: pet.KindNumber = (GridView1.Rows[e.RowIndex].FindControl("TextBox3") as TextBox).Text;
行 93: pet.Heat = Convert.ToInt16((GridView1.Rows[e.RowIndex].FindControl("Label1") as Label).Text);

源文件: F:\vsproject\PetCare\PetCare\WebForm1.aspx.cs 行: 91