GridView绑定记录为空显示表头

protected void btnQuery_Click(object sender, EventArgs e)
{
string queryCondition = "1=1";
string name = this.tbName.Text.Trim();
string idCode = this.tbIDCode.Text.Trim();
string flowInDate = this.tbFlowInDate.Text.Trim();
string mateName = this.tbMateName.Text.Trim();
string mateIdCode = this.tbMateIDCode.Text.Trim();
string reportDate = this.tbReportDate.Text.Trim();
string verifyState = this.ddlVerifyState.SelectedItem.Text;
if (!name.Equals(""))
{
queryCondition = queryCondition + " and Name='" + name + "'";
}
if (!idCode.Equals(""))
{
queryCondition = queryCondition + " and ID_Code='" + idCode + "'";
}
if (!flowInDate.Equals(""))
{
queryCondition = queryCondition + " and FlowIn_Date='" + Convert.ToDateTime(flowInDate) + "'";
}
if (!mateName.Equals(""))
{
queryCondition = queryCondition + " and Mate_Name='" + mateName + "'";
}
if (!mateIdCode.Equals(""))
{
queryCondition = queryCondition + " and Mate_IDCode='" + mateIdCode + "'";
}
if (!reportDate.Equals(""))
{
queryCondition = queryCondition + " and Report_Date='" + Convert.ToDateTime(reportDate) + "'";
}
if (!verifyState.Equals("--请选择--"))
{
queryCondition = queryCondition + " and Verify_Stat='" + verifyState + "'";
}
//this.gvFlowing.DataSource = bibRecDataBll.GetByWhere(queryCondition);
//this.gvFlowing.DataBind();
DataSet ds = bibRecDataBll.GetByWhere(queryCondition);
if (ds.Tables[0].Rows.Count == 0)
{
DataTable dt = new DataTable();
dt.Columns.Add("FlowIn_ID");
dt.Columns.Add("FI_H_ID");
dt.Columns.Add("Name");
dt.Columns.Add("ID_Code");
dt.Columns.Add("FlowIn_Date");
dt.Columns.Add("MarryStat");
dt.Columns.Add("Mate_Name");
dt.Columns.Add("Verify_Stat");
dt.Rows.Add(dt.NewRow());
this.gvFlowing.DataSource = dt;
this.gvFlowing.DataBind();
int columnCount = dt.Columns.Count;
this.gvFlowing.Rows[0].Cells.Clear();
this.gvFlowing.Rows[0].Cells.Add(new TableCell());
this.gvFlowing.Rows[0].Cells[0].ColumnSpan = columnCount;
this.gvFlowing.Rows[0].Cells[0].Text = "没有记录";
this.gvFlowing.Rows[0].Cells[0].Style.Add("text-align", "center");

}
else
{
this.gvFlowing.DataSource = bibRecDataBll.GetByWhere(queryCondition);
this.gvFlowing.DataBind();
}

}