数据集行计数的空引用

Question

这是我的计数。尝试检查数据集的行数，但得到错误：

  

对象引用未设置为if处的对象实例   （ds.Tables [＆＃34; GetCaseInformationByCaseStatusANDCaseNumber＆＃34;] Rows.Count。   ！= 0）。

请帮忙。

 using (SqlCommand GetCaseInformationByCaseStatusANDCaseNumberSP = new SqlCommand("GetCaseInformationByCaseStatusANDCaseNumberSP", Apptestconn))
 {
     GetCaseInformationByCaseStatusANDCaseNumberSP.CommandType = CommandType.StoredProcedure;
     GetCaseInformationByCaseStatusANDCaseNumberSP.Parameters.AddWithValue("@UserName", "nguyenlc");
     GetCaseInformationByCaseStatusANDCaseNumberSP.Parameters.AddWithValue("@CaseStatus", TextBox1.Text);
     GetCaseInformationByCaseStatusANDCaseNumberSP.Parameters.AddWithValue("@CaseNumber", CaseNumberTextBox.Text);
     GetCaseInformationByCaseStatusANDCaseNumberSP.ExecuteNonQuery();

     SqlDataAdapter da = new SqlDataAdapter(GetCaseInformationByCaseStatusANDCaseNumberSP);
     DataSet ds = new DataSet();
     da.Fill(ds, "GetCaseInformationByCaseStatusANDCaseNumberTable");
     ReviewCaseStatusListView.DataSource = ds.Tables["GetCaseInformationByCaseStatusANDCaseNumberTable"];
     ReviewCaseStatusListView.DataBind();

     if (ds.Tables["GetCaseInformationByCaseStatusANDCaseNumberTable"] != null)
     {
         if (ds.Tables["GetCaseInformationByCaseStatusANDCaseNumber"].Rows.Count != 0)
         {
             CaseUploadHistoryLabel.Text = "Case Upload History:";
             CaseUploadHistoryLabel.Visible = true;
          }

      }
}