For-loop doesn't complete all iterations - vb.net

Question

I have problem with this - I try to send broadcast SMS using AT Commands in my system. After that the SMS content will be stored in my database. My store content SMS function works well. I can store all my SMS content that I send, but the send function just sends message to my first data on my datagridview.
Please help me to deal with this - I posted my code below
Private Sub ButtonKirim_Click(sender As Object, e As EventArgs) Handles ButtonKirim.Click
Dim noPel As String
Dim isiPesan As String = ""
Dim tgl As Date = Now.Date
Dim strReplace(2) As String
Dim strIsi(2) As String
Dim tagBulan As String = "<bulan>"
Dim tagtagihan As String = "<tagihan>"
Dim tagLokasi As String = "<lokasi>"
Dim pesanKirim As String = ""
My.Settings.SettingPesan = RichTextBoxPesan.Text
My.Settings.Save()
'Label4.Text = isiPesan
For pelanggan As Integer = 0 To DataGridViewKirimPesan.RowCount - 1
'mengirim pesan/send message
noPel = DataGridViewKirimPesan.Rows(pelanggan).Cells(3).Value()
strReplace(0) = tagBulan
strReplace(1) = tagtagihan
strReplace(2) = tagLokasi
strIsi(0) = DataGridViewKirimPesan.Rows(pelanggan).Cells(4).Value
strIsi(1) = DataGridViewKirimPesan.Rows(pelanggan).Cells(5).Value
strIsi(2) = DataGridViewKirimPesan.Rows(pelanggan).Cells(6).Value
isiPesan = RichTextBoxPesan.Text
For i As Integer = LBound(strReplace) To UBound(strReplace)
isiPesan = isiPesan.Replace(strReplace(i), strIsi(i))
Next
SendMessage(noPel, isiPesan)
''menyimpan pesan keluar ke sms_terkirim/this query store my content SMS to table
Dim sqlSmsKeluar As String = "INSERT INTO sms_terkirim (`tgl_sms`,`id_pelanggan`, `isi_sms`) VALUES ( NOW()," & DataGridViewKirimPesan.Rows(pelanggan).Cells(0).Value & " , '" & isiPesan & "');"
cudMethod(sqlSmsKeluar)
MsgBox(sqlSmsKeluar)
'ProgressBarKirimPesan.Increment(1)
Next
'MsgBox("Pesan Sukses Terkirim")
' Catch ex As Exception
' MsgBox("Pesan Gagal Terkirim" + ex.Message)
'End Try
' End If
End Sub
and this code is AT Command to send message
Public Sub SendMessage(ByVal NomorPelanggan As String, ByVal IsiPesan As String)
If SerialModem.IsOpen() Then
With SerialModem
.Write("AT" & vbCrLf)
Threading.Thread.Sleep(100)
.Write("AT+CMGF=1" & vbCrLf)
Threading.Thread.Sleep(100)
.Write("AT+CMGS=" & Chr(34) & NomorPelanggan & Chr(34) & vbCrLf)
Threading.Thread.Sleep(100)
.Write(IsiPesan & vbCrLf & Chr(26))
Threading.Thread.Sleep(100)
End With
Else
MsgBox("Modem Belum Tersambung")
End If
End Sub