Sql query not working

Question

SqlDataAdapter sda = new SqlDataAdapter("select scode from result where Enrollno ='" + Label7.Text + "'", con);

DataTable dt = new DataTable();

sda.Fill(dt);

int c = dt.Rows.Count;

if (c != 0)

{

Label8.Text ="Sorry You Have been already Given Exam";

}

Its not working

when i given Not paper1 (scode) its works and insert command .

after that when i want given paper2(scode) its say Sorry You Have been already Given Exam";

but i not given paper2.

One Enrollment No. also give paper1 and paper2, paper3 how....?

 

else

{

SqlCommand cmd = new SqlCommand("insert into result(Enrollno,scode,TotalQuestion,TotalCorrectAnswer,TotalWrongAnswer,Examdate) values (" + Label7.Text + ",'" + DropDownList1.Text + "','" + a + "','" + count + "','" + b + "','" + Label5.Text + "')", con);

con.Open();

cmd.ExecuteNonQuery();

con.Close();

}