What is wrong with filling this datatable in asp.net - asp.net

Question

I am trying to fill a list from a database. Here is my code:
string cur = dInstructorSelect.SelectedValue.Substring(dInstructorSelect.SelectedValue.IndexOf(" - ") + 3);
SqlCommand cmdInsCourses = new SqlCommand("select * from CourseTable where InstructorID=#cur", con);
cmd.Parameters.AddWithValue("#cur", cur);
SqlDataAdapter da = new SqlDataAdapter(cmdInsCourses);
DataTable dt = new DataTable();
da.Fill(dt);
Here, i declare a string variable cur, which returns 4 as i expect. The problem is, when i debugged, there is an error saying that Must declare the scalar variable "#cur". I cannot see what is problematic here. Can anyone help?
Thanks
Edit: Here is the full code:
SqlConnection con = new SqlConnection();
con.ConnectionString = Userfunctions.GetConnectionString();
int result;
string queryCourseCount = "select count (*) from CourseTable";
SqlCommand countCommand = new SqlCommand(queryCourseCount, con);
con.Open();
int courseCount = 1001 + Convert.ToInt32(countCommand.ExecuteScalar());
string crn = (MyGlobals.currentYear % 100).ToString() + (MyGlobals.currentTerm == "Spring" ? 2 : 1) + courseCount.ToString().Substring(1, 3);
string instructor = dInstructorSelect.SelectedValue.Substring(dInstructorSelect.SelectedValue.IndexOf(" - ")+3);
string subject = dSubject.SelectedValue, courseNumber=tCourse.Text, courseName= tCourseName.Text ;
string courseDescription = tCourseDescription.Text, capacity=tCapacity.Text;
string currentTerm=MyGlobals.currentTerm + " " + MyGlobals.currentYear.ToString();
string level=dLevel.SelectedValue, credit=tCredit.Text;
string query1 = "insert into CourseTable(InstructorID,CourseCode,CourseNumber,CourseName,Term, CRN,Level,Credit,Description,Capacity) values(#instructor,#subject,#courseNumber,#courseName,#currentTerm,#crn,#level,#credit,#courseDescription,#capacity)";
SqlCommand cmd = new SqlCommand(query1, con);
cmd.Parameters.AddWithValue("#instructor", instructor);
cmd.Parameters.AddWithValue("#subject", subject);
cmd.Parameters.AddWithValue("#courseNumber", courseNumber);
cmd.Parameters.AddWithValue("#courseName", courseName);
cmd.Parameters.AddWithValue("#currentTerm", currentTerm);
cmd.Parameters.AddWithValue("#crn", crn);
cmd.Parameters.AddWithValue("#level", level);
cmd.Parameters.AddWithValue("#credit", credit);
cmd.Parameters.AddWithValue("#courseDescription", courseDescription);
cmd.Parameters.AddWithValue("#capacity", capacity);
string query2 = "";
string query3 = "";
if (cbPreq1.Checked)
{
query2 = "insert into PrereqTable(CourseCode,CourseNumber,Term,pCourseCode,pCourseNumber) values ('"
+ dSubject.SelectedValue + "'" + "," + "'" + tCourse.Text + "'" + "," + "'" + MyGlobals.currentTerm + " " + MyGlobals.currentYear.ToString()
+ "'" + "," + "'" + dPrereq1.SelectedValue.Substring(0, dPrereq1.SelectedValue.Length - 3) + "'" + "," + "'" + dPrereq1.SelectedValue.Substring(dPrereq1.SelectedValue.Length - 3, 3) + "'" + ")";
}
if (cbPreq2.Checked)
{
query3 = "insert into PrereqTable(CourseCode,CourseNumber,Term,pCourseCode,pCourseNumber) values ('"
+ dSubject.SelectedValue + "'" + "," + "'" + tCourse.Text + "'" + "," + "'" + MyGlobals.currentTerm + " " + MyGlobals.currentYear.ToString()
+ "'" + "," + "'" + dPrereq2.SelectedValue.Substring(0, dPrereq2.SelectedValue.Length - 3) + "'" + "," + "'" + dPrereq2.SelectedValue.Substring(dPrereq2.SelectedValue.Length - 3, 3) + "'" + ")";
}
string query4="";
if (cbtime1.Checked)
{
query4 = "insert into TimeTable(CourseCode, CourseNumber, Term, StartHour, EndHour, Day) values ('"
+ dSubject.SelectedValue + "'" + "," + "'" + tCourse.Text + "'" + "," + "'" + MyGlobals.currentTerm + " " + MyGlobals.currentYear.ToString()
+ "'" + "," + "'" + dHourStart.SelectedValue + "'" + "," + "'" + dHourEnd.SelectedValue + "'" + "," + "'" + dDay.SelectedValue + "'" + ")";
}
string query5 = "";
if (cbtime2.Checked)
{
query5 = "insert into TimeTable(CourseCode, CourseNumber, Term, StartHour, EndHour, Day) values ('"
+ dSubject.SelectedValue + "'" + "," + "'" + tCourse.Text + "'" + "," + "'" + MyGlobals.currentTerm + " " + MyGlobals.currentYear.ToString()
+ "'" + "," + "'" + dHourStart2.SelectedValue + "'" + "," + "'" + dHourEnd2.SelectedValue + "'" + "," + "'" + dDay2.SelectedValue + "'" + ")";
}
string query6="";
if (cbtime3.Checked)
{
query6 = "insert into TimeTable(CourseCode, CourseNumber, Term, StartHour, EndHour, Day) values ('"
+ dSubject.SelectedValue + "'" + "," + "'" + tCourse.Text + "'" + "," + "'" + MyGlobals.currentTerm + " " + MyGlobals.currentYear.ToString()
+ "'" + "," + "'" + dHourStart3.SelectedValue + "'" + "," + "'" + dHourEnd3.SelectedValue + "'" + "," + "'" + dDay3.SelectedValue + "'" + ")";
}
SqlCommand cmd1, cmd2, cmd3, cmd4, cmd5, cmd6;
bool correctTime = false;
List<String> timeTable = new List<string>();
List<Course>instCourses = new List<Course>();
string tableName = "InstructorTable";
// String name = "", surname = "", email = "";
// CreateUser(con, tableName, ref name, ref surname, ref email);
// MyGlobals.instructor = new Instructor(Convert.ToInt32(idBox.Text), "Active", email, name, surname, passwordBox.Text);
string cur = dInstructorSelect.SelectedValue.Substring(dInstructorSelect.SelectedValue.IndexOf(" - ") + 3);
SqlCommand cmdInsCourses = new SqlCommand("select * from CourseTable where InstructorID=#cur", con);
cmd.Parameters.AddWithValue("#cur", cur);
SqlDataAdapter da = new SqlDataAdapter(cmdInsCourses);
DataTable dt = new DataTable();
da.Fill(dt);
Note: I know there are some queries that are not parametrized, i will fix them.

Answer 1

Try prefixing your parameter with #:
cmdInsCourses.Parameters.AddWithValue("#cur", cur);

Answer 2

Try adding the scalar variable "#cur" rather than "cur":
cmd.Parameters.AddWithValue("#cur", cur);

Answer 3

Try like this...
SqlCommand cmdInsCourses =
new SqlCommand("select * from CourseTable where InstructorID=#cur", con);
cmdInsCourses.Parameters.Add("cur", SqlDbType.VarChar).Value = cur;
EDIT : The Problem lies that you are adding parameters to cmd, not to cmdInsCourses, I have changed the code, just look into that.