VERSION 5.00
Begin VB.Form Form1 
   Caption         =   "Form1"
   ClientHeight    =   8790
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   9090
   LinkTopic       =   "Form1"
   ScaleHeight     =   8790
   ScaleWidth      =   9090
   StartUpPosition =   3  'Windows Default
   Begin VB.TextBox Text1 
      Height          =   285
      Left            =   4800
      TabIndex        =   3
      Text            =   "Text1"
      Top             =   1440
      Width           =   2175
   End
   Begin VB.CommandButton Command1 
      Caption         =   "Command1"
      Height          =   375
      Left            =   5040
      TabIndex        =   2
      Top             =   2400
      Width           =   1455
   End
   Begin VB.ListBox List2 
      Height          =   2010
      Left            =   2640
      TabIndex        =   1
      Top             =   1200
      Width           =   1695
   End
   Begin VB.ListBox List1 
      Height          =   2010
      Left            =   840
      TabIndex        =   0
      Top             =   1200
      Width           =   1815
   End
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Private Sub Command1_Click()
If List1.ListCount = 0 Then
MsgBox "no list select"
Else
If List1.ListIndex = List1.ListCount - 1 Then
MsgBox "list end "
Else
List1.ListIndex = List1.ListIndex + Val(1)
End If
End If

End Sub

Private Sub Form_Load()
List1.AddItem "a"
List1.AddItem "b"
List2.AddItem "2222"
List2.AddItem "5555"
End Sub

Private Sub List1_Click()
List2.ListIndex = List1.ListIndex
End Sub

Private Sub List2_Click()
If List1.ListIndex = List1.ListCount - 1 Then
MsgBox "list end"
Else
' you sending code here , with number = list2.text
End If
End Sub