error in insert coding

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C#

sorry i am a newbie and my friend found out some coding error.
i am not able to understand what the problem is.

SqlConnection conn = new SqlConnection();
            conn.ConnectionString = @"Data Source=.\SQLEXPRESS;AttachDbFilename=E:\project\Projects\labelnameinsecondformtry\labelnameinsecondformtry\Database1.mdf;Integrated Security=True;User Instance=True";
            SqlCommand cmd = new SqlCommand();
            cmd.Connection = conn;
            conn.Open();
            try
            {
                cmd.CommandText = "Insert into Table2 values (username)";
                cmd.Parameters.Add("@username", SqlDbType.VarChar).Value =textBox1.Text;
                cmd.ExecuteNonQuery();
            }
            finally
            {
                conn.Close();
                MessageBox.Show("hello welcome");
            }

the error is comming new executenonquery and saying that

Invalid column name 'username' but username column us there in my database whats the real problem in this coding