connect database ไม่ติดอ่ะค่ะ ใครก็ได้ช่วยหน่อยนะคะ

Imports Microsoft.VisualBasic
Imports System.Data.SqlClient
Imports System.Data

Public Class insertToDB
    Dim conDB As New connectDB
    Dim conn As New SqlConnection(conDB.connection)

    Public Sub insertTeacher(ByVal Teacher_ID As String, ByVal Teacher_Name As String, ByVal Teacher_Room As String, ByVal Teacher_Email As String, ByVal Teacher_Telephone As String)
        Dim sql As String = "insert into Teacher values(?,?,?,?,?)"
        Dim cmd As New SqlCommand(sql, conn)

        With conn
            If .State = ConnectionState.Open Then .Close()
            .Open()
        End With

        With cmd
            .Parameters.Add("?", SqlDbType.NChar, 8, "Teacher_ID").Value = Teacher_ID
            .Parameters.Add("?", SqlDbType.VarChar, 30, "Teacher_Name").Value = Teacher_Name
            .Parameters.Add("?", SqlDbType.NChar, 6, "Teacher_Room").Value = Teacher_Room
            .Parameters.Add("?", SqlDbType.VarChar, 30, "Teacher_Email").Value = Teacher_Email
            .Parameters.Add("?", SqlDbType.NChar, 10, "Teacher_Telephone").Value = Teacher_Telephone
            .ExecuteNonQuery()
        End With
    End Sub

    Function runIDinsert(ByVal tableName As String, ByVal column As String) As Integer
        Dim sql As String = "select" & column & "from" & tableName & "order by" & column
        Dim da As New SqlDataAdapter(sql, conn)
        Dim ds As New DataSet
        da.Fill(ds, "Teacher_ID")

        Dim id As Integer
        If ds.Tables("Teacher_ID").Rows.Count <> 0 Then
            id = ds.Tables("Teacher_ID").Rows(0).Item(column) + 1
        Else
            id = 1
        End If
        Return id
    End Function

    Public Sub insertStudent(ByVal Student_ID As String, ByVal Student_Name As String, ByVal Student_GPA As Integer, ByVal Student_Address As String, ByVal Student_Gender As Char, ByVal Student_Bestfriend As String, ByVal Student_Telephone As String, ByVal Student_Email As String)
        Dim sql As String = "insert into Student values(?,?,?,?,?,?,?,?)"
        Dim cmd As New SqlCommand(sql, conn)

        With conn
            If .State = ConnectionState.Open Then .Close()
            .Open()
        End With

        With cmd
            .Parameters.Add("?", SqlDbType.NChar, 11, "Student_ID").Value = Student_ID
            .Parameters.Add("?", SqlDbType.VarChar, 30, "Student_Name").Value = Student_Name
            .Parameters.Add("?", SqlDbType.Float, 4, "Student_GPA").Value = Student_GPA
            .Parameters.Add("?", SqlDbType.VarChar, 70, "Student_Address").Value = Student_Address
            .Parameters.Add("?", SqlDbType.Char, 1, "Student_Gender").Value = Student_Gender
            .Parameters.Add("?", SqlDbType.VarChar, 30, "Student_Bestfriend").Value = Student_Bestfriend
            .Parameters.Add("?", SqlDbType.NChar, 10, "Student_Telephone").Value = Student_Telephone
            .Parameters.Add("?", SqlDbType.VarChar, 30, "Student_Email").Value = Student_Email
            .ExecuteNonQuery()
        End With
    End Sub
End Class