ติดโค๊ด update ค่ะ VB2005 error syntax error in update statement ค่ะรบกวนด้วยนะค่ะ

ImportsSystem.Data
ImportsSystem.Data.OleDb
 
PublicClass Change
    Dim myConn As OleDbConnection
    Dim sql As String
    Dim da As OleDbDataAdapter
    Dim ds As New DataSet
    Dim da1 As OleDbDataAdapter
    Dim myCmd As OleDb.OleDbCommand
 
 
    Private Sub FrmCommand_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        myConn = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; Data Source=C:\PharmacySystem.mdb;")
        myConn.Open()
 
    End Sub
    Private Sub BT3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BT3.Click
        Dim sqlem As String
        Dim currentem As String
        Dim dr As DataRow
        Dim pk(1) As DataColumn
        Dim Isfind As Boolean = False
 
 
        If TextBox1.Text = "" Then Exit Sub
 
        sqlem = "SELECT Em_ID ,First_Name FROM Employees"
 
        da = New OleDbDataAdapter(sqlem, myConn)
        da.Fill(ds, "Employees")
 
        Try
 
            ListBox1.Items.Clear()
 
            pk(0) = ds.Tables("Employees").Columns("Em_ID")
 
            ds.Tables("Employees").PrimaryKey = pk
 
            dr = ds.Tables("Employees").Rows.Find(TextBox1.Text)
 
            If dr IsNot Nothing Then
                currentem = CStr(dr(0)) & "       " & CStr(dr(1))
 
                ListBox1.Items.Add(currentem)
 
            Else
                ListBox1.Items.Add("ไม่มีชื่อที่ต้องการ")
            End If
 
        Catch ex As Exception
 
            MsgBox("NO DATA")
 
        End Try
        Dim com As New OleDbCommand
 
        With com
            .CommandText = "[serchem]"
            .CommandType = CommandType.StoredProcedure
            .Connection = myConn
 
            da1 = New OleDbDataAdapter(com)
 
            da1.SelectCommand.Parameters.Add("@Em_ID", OleDbType.LongVarChar).Value = TextBox1.Text
 
            If Isfind = True Then
                ds.Tables("Employees").Clear()
 
            End If
 
            da1.Fill(ds, "Employees")
 
            If ds.Tables("Employees").Rows.Count <> 0 Then
                Isfind = True
 
 
                TextBox1.Focus()
            End If
 
        End With
 
    End Sub
 
 
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
 
        Dim a As String
        Dim b As String
        Dim c As Integer
 
 
 
        a = CStr(TextBox1.Text)
        b = CStr(TextBox2.Text)
        c = CInt(TextBox3.Text)
 
 
 
        myCmd = New OleDbCommand(" UPDATE Employees SET  User = '" & b & "',Password = '" & c & "'" & _
                                " WHERE Em_ID =  " & a, myConn)
 
 
 
        Try
            myCmd.ExecuteNonQuery()
            MessageBox.Show("แก้ไขข้อมูลเรียบร้อยแล้ว", "ผลการทำงาน", _
                            MessageBoxButtons.OK, MessageBoxIcon.Information)
 
        Catch ErrFromInsert As Exception
            MessageBox.Show("ไม่สามารถแก้ไขข้อมูลใหม่ได้กรุณาตรวจสอบชื่อลูกค้า! "& _
                            ErrFromInsert.Message, "ข้อผิดพลาด", _
                           MessageBoxButtons.OK, MessageBoxIcon.Error)
        End Try
    End Sub
 
EndClass