我这个combobox控件下拉框数据绑定成功没，求帮我看下，为啥我运行选项为空呀

SqlConnection con = new SqlConnection("server=BF-20190121OIUV;database=ScienceManSys;Uid = sa; Pwd = gg5196288");
SqlDataAdapter da = new SqlDataAdapter("SELECT * FROM [dbo].[获奖分类表]", con);
DataSet ds = new DataSet();
da.Fill(ds, "[dbo].[获奖分类表]");
DataTable dtGroup = ds.Tables["[dbo].[获奖分类表]"];

        comboBox1.DataSource = dtGroup;
    
        comboBox1.DisplayMember = "AwardCategory"; //显示到comboBox的值
        comboBox1.ValueMember = "编号"; //comboBox真正的值

        this.comboBox1.SelectedIndex = -1;____

comboBox1.DataSource = dtGroup;

    comboBox1.DisplayMember = "AwardCategory"; //显示到comboBox的值
    comboBox1.ValueMember = "编号"; //comboBox真正的值

改为

    comboBox1.DisplayMember = "AwardCategory"; //显示到comboBox的值
    comboBox1.ValueMember = "编号"; //comboBox真正的值

comboBox1.DataSource = dtGroup;

da.Fill(ds);
DataTable dtGroup = ds.Tables[0];
comboBox1.DataSource = dtGroup;

private void FrmHonourAdd_Load(object sender, EventArgs e)
{
SqlConnection con = new SqlConnection("Data Source=BF-20190121OIUV;initial Catalog=ScienceManSys;User ID=sa;Password=gg5196288;");
con.Open();
SqlDataAdapter da = new SqlDataAdapter("SELECT * FROM [dbo].[获奖分类表]", con);
DataSet ds = new DataSet();
da.Fill(ds);
DataTable dtGroup = ds.Tables["[dbo].[获奖分类表]"];

        comboBox1.DisplayMember = "AwardCategory"; //显示到comboBox的值
        comboBox1.ValueMember = "编号"; //comboBox真正的值

        comboBox1.DataSource = dtGroup;
        this.comboBox1.SelectedIndex = -1;
      
    
      
    }