Null reference at dataset row count

Question

Here is my count. Trying to check row count at of dataset but getting the error:

Object reference not set to an instance of an object at if (ds.Tables["GetCaseInformationByCaseStatusANDCaseNumber"].Rows.Count != 0).

Please help.

 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;
          }

      }
}