Object reference not set to an instance of an object ช่วยที่ครับผม

Option Explicit On
Option Strict On
Imports System.Text
Imports System.Data
Imports System.Data.SqlClient
Imports System.Drawing.Drawing2D
Public Class frmAcademic
    Dim Conn As SqlConnection
    Dim com As SqlCommand
    Dim tr As SqlTransaction
    Dim sb As StringBuilder
    Dim dr As SqlDataReader
    Private Sub frmAcademic_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim strConn As String
        strConn = DBConnString.strConn

        Conn = New SqlConnection()
        With Conn
            If .State = ConnectionState.Open Then .Close()
            .ConnectionString = strConn
            .Open()
        End With
    End Sub
    Private Sub cmdAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdAdd.Click
        If MessageBox.Show("Do you want to save", "Confirm", MessageBoxButtons.YesNo, MessageBoxIcon.Question) = Windows.Forms.DialogResult.Yes Then

            tr = Conn.BeginTransaction()

            Try
                sb = New StringBuilder()
                sb.Append("INSERT INTO Academic (AcademicID,AcademicSaveDate,AcademicYear,SemesterNo,StartDate,EndDate)")
                sb.Append(" VALUES (@AcademicID,@AcademicSaveDate,@AcademicYear,@SemesterNo,@StartDate,@EndDate)")


                Dim sqlAdd As String
                sqlAdd = sb.ToString()

                With com
                    .CommandText = sqlAdd
                    .CommandType = CommandType.Text
                    .Connection = Conn
                    .Transaction = tr
                    .Parameters.Clear()
                    .Parameters.Add("@AcademicID", SqlDbType.NVarChar).Value = txtAcademicID.Text.Trim()
                    .Parameters.Add("@AcademicSaveDate", SqlDbType.DateTime).Value = dtpSaveDate.Value
                    .Parameters.Add("@AcademicYear", SqlDbType.NVarChar).Value = txtAcademicYear.Text.Trim()
                    .Parameters.Add("@SemesterNo", SqlDbType.NVarChar).Value = txtSemester.Text.Trim()
                    .Parameters.Add("@StartDate", SqlDbType.DateTime).Value = dtpStartDate.Value
                    .Parameters.Add("@EndDate", SqlDbType.DateTime).Value = dtpEndDate.Value

                    .ExecuteNonQuery()
                End With
                tr.Commit()
                MessageBox.Show("Save Sucess !!! ", "Confirm", MessageBoxButtons.OK, MessageBoxIcon.Information)
            Catch ex As Exception
                MessageBox.Show("Erorr " & ex.Message, "Alert ", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
                tr.Rollback()
            End Try
        End If
    End Sub
End Class