Data grid Bonding Error

private void dataRepeater1_DrawItem(object sender, Microsoft.VisualBasic.PowerPacks.DataRepeaterItemEventArgs e)
{
Label txtExample = (Label)e.DataRepeaterItem.Controls["label1"] as Label;
Label label2 = (Label)e.DataRepeaterItem.Controls["label2"] as Label;
Label label3 = (Label)e.DataRepeaterItem.Controls["label3"] as Label;
Label label4 = (Label)e.DataRepeaterItem.Controls["label4"] as Label;
var grid = e.DataRepeaterItem.Controls["dataGridView1"] as DataGridView;
if (txtExample.Text != null && label2.Text != null && label3.Text != null && label4.Text != null)
{
SqlDataAdapter daa = new SqlDataAdapter(@"select Question,Fullmarks from dbo.tbl_QuestionConfig where Sectiontype='" + label2.Text + "' and Questiontype='" + label3.Text + "' and Subject='" + label4.Text + "'", con);
DataTable dtt = new DataTable();
daa.Fill(dtt);
if (dtt.Rows.Count > 0)
{
dataGridView1.DataSource = dtt;
dataGridView1.AutoGenerateColumns = false;
dataGridView1.EnableHeadersVisualStyles = false;
dataGridView1.ColumnHeadersDefaultCellStyle.BackColor = Color.LightSeaGreen;
foreach (DataGridViewRow r in dataGridView1.Rows)
{
r.DefaultCellStyle.BackColor = Color.LightCyan;
}
}
}