Visual Basic - problemas con el error 13 no coinciden los datos

BUENO NECESITO UNA AYUDA URGENTE SE QUE MUCHOS DE USTEDES PODRAN AYUDARME ESTOY INICIALIZANDOME EN ESTO DE VISUAL BASIC , EN ESTE MOMENTO TRATO DE ACTUALIZAR UNOS CAMPOS ESPECIFICOS EN UNA TABLA (BASE DE DATOS EN SQL SERVER), UTILIZANDO UN ADO PERO ME DA UN ERROR EN EL QUERY (ERROR= 13 NO COINCIDEN LOS DATOS)
SOSPECHO QUE SON LAS ' ' EN LOS DATOS TIPO INTEGER, PERO NOSE COMO HACERLO

AQUI COPIO MI CODIGO A VER SI ME AYUDAN UN POCO, PLEASE!

Option Explicit
Dim m_rs As ADODB.Recordset

Private Sub cmdconsultar_Click()
Dim rA As Long

Dim Xq As String
Dim xcagru As Double
Dim xcuni As Double
Dim xpreuni As Double
Dim xfechau As String
Dim xcod As String

xcod = Me.txtcod1
Set m_rs = Nothing
lview.ListItems.Clear
Me.lview.Refresh

If Not Me.txtcod1 = "" Then
Xq = "select * from productos where cod_pro='" + xcod + "'"

Debug.Print Xq
Dim Rs As ADODB.Recordset
Set Rs = New ADODB.Recordset
Rs.Open Xq, adocn, adOpenForwardOnly, adLockReadOnly
If Not Rs.EOF Then
Set m_rs = Rs
findnext
End If
Else
MsgBox "Debe Indicar un Codigo de Producto"
Me.txtcod1.SetFocus
End If

End Sub
Private Sub findnext()
Dim li As MSComctlLib.ListItem
Dim ls As MSComctlLib.ListItems
Set ls = Me.lview.ListItems
Dim xcagru As Double
Dim xcuni As Double
Dim xpreuni As Double
Dim xfechau As String
Dim j As Long


If m_rs Is Nothing Then
Exit Sub
End If

j = 0

Do While j < 60
If m_rs.EOF = True Then
Exit Do
End If

Set li = ls.Add(, , m_rs!cod_pro)
li.Tag = m_rs!pro_id
li.SubItems(1) = m_rs!grp_pro
li.SubItems(2) = m_rs!mrc_pro
li.SubItems(3) = m_rs!des_pro
li.SubItems(4) = m_rs!emin_pro
li.SubItems(5) = m_rs!emax_pro
li.SubItems(6) = m_rs!cagru_pro
xcagru = m_rs!cagru_pro
li.SubItems(7) = m_rs!cuni_pro
xcuni = m_rs!cuni_pro
li.SubItems(8) = m_rs!cant_pro
li.SubItems(9) = m_rs!preuni_pro
xpreuni = m_rs!preuni_pro
li.SubItems(10) = m_rs!fentra_pro
xfechau = m_rs!fentra_pro
m_rs.MoveNext
j = j + 1
Loop
Me.txtcagru = xcagru
Me.txtcuni = xcuni
Me.txtpreuni = xpreuni
Me.txtfechau = xfechau

End Sub

Private Sub CMDEXIT_Click()
Unload Me
End Sub

Private Sub cmdok_Click()
If validar = False Then
Exit Sub
End If
Dim rA As Long

Dim Xq As String
Dim xcagru2 As Integer
Dim xcuni2 As Integer
Dim xpreuni2 As Integer
Dim xcagru As Integer
Dim xcuni As Integer
Dim xpreuni As Integer
Dim xcagru_t As Integer
Dim xcuni_t As Integer
Dim xpeuni_t As Integer
Dim xcant As Integer
Dim xcod As String
Dim xfecha As String
Dim li As MSComctlLib.ListItem

xcagru2 = Me.txtcagru2
xcuni2 = Me.txtcuni2
xpreuni = Me.txtpreuni
xcod = Me.txtcod1
xfecha = Me.txtfecha
xcuni = Me.txtcuni
xcagru = Me.txtcagru

'Operaciones aritmeticas
xcuni_t = xcuni2 + xcuni
xcagru_t = Val(xcagru2 + xcagru)
xcant = Val(xcuni_t * xcagru_t)
'**************************
'Aqui me da el error
Xq = "update productos set cuni_pro='" + xcuni_t + "',cagru_pro='" + xcagru_t + "',cant_pro='" + xcant + "',preuni_pro='" + xpreuni + "',fentra_pro='" + xfecha + "' where cod_pro='" + xcod + "'"

Debug.Print Xq
rA = 0
On Error Resume Next
adocn.Execute Xq, rA
On Error GoTo 0
If (rA > 0) Then
limpiar
Me.txtcod1.SetFocus
Exit Sub
End If
MsgBox "No se pudo incluir el registro examine los datos", vbCritical, Me.Caption
End Sub

Private Sub limpiar()
Me.txtcagru2 = ""
Me.txtcod1 = ""
Me.txtcuni2 = ""
Me.txtfecha = ""
Me.txtpreuni2 = ""

End Sub
Private Function validar() As Boolean
validar = False

If Me.txtcagru2 = "" Then
Me.txtcagru2.SetFocus
Exit Function
End If
If Me.txtcuni2 = "" Then
Me.txtcuni2.SetFocus
Exit Function
End If
If Me.txtpreuni2 = "" Then
Me.txtpreuni2.SetFocus
Exit Function
End If

validar = True
End Function

Private Sub Form_Load()
'cargo el icono del formulario
Me.Icon = m_Frmmain.Icon

'cargo la fecha del sistema
Me.txtfecha.Text = CStr(Day(Now)) _
+ "/" + CStr(Month(Now)) _
+ "/" + CStr(Year(Now))

'cargo los valores del lview
Set m_rs = Nothing
Me.lview.ColumnHeaders.Item(1).Width = 1000
Me.lview.ColumnHeaders.Item(2).Width = 4000
Me.lview.ColumnHeaders.Item(3).Width = 2000
Me.lview.ColumnHeaders.Item(4).Width = 2000
Me.lview.ColumnHeaders.Item(5).Width = 2000
Me.lview.ColumnHeaders.Item(6).Width = 1500
Me.lview.ColumnHeaders.Item(7).Width = 2000
Me.lview.ColumnHeaders.Item(8).Width = 2000
Me.lview.ColumnHeaders.Item(9).Width = 2000
Me.lview.ColumnHeaders.Item(10).Width = 2000
Me.lview.ColumnHeaders.Item(11).Width = 2000

End Sub

Hola,
creo que si que el problema va a ser ese, solo las cadenas de texto tienen que ir entre ' '.

espero te sirva

un saludo