CodeBase-Visual basic

Hello,

How do I open a databe file using codebase/visual basic?

Here is my code but it won't work

--------------------------
Sub Main()

Dim i As Integer

cb = code4init()

If cb = 0 Then
MsgBox "Failed to initialize.", 48, "Fatal Error"
End If

i = code4errOpen(cb, 0)

some code
frmServUpd.WindowState = 2
frmServUpd.Show 1

'close all input sources

If cb <> 0 Then
i = code4initUndo(cb)
End if

End Sub

----------------------------------------------

Sub OpenDB(fn As String)

Dim i As Integer
Dim a As String, b As String
Dim premTag As Long

frmServUpd.MousePointer = 11
frmServUpd.lblMsg1.Visible = True
frmServUpd.Refresh

'close currently open DB
If DB <> 0 Then i = d4close(DB)

'open new DB
DB = d4open(cb, fn)
If DB = 0 Then
i = code4errorCode(cb, 0)
b = "Failed to open " + fn
MsgBox b, 48, "Error"
MsgBox "Error code = " & Format$(i), 48, "Error"
Exit Sub
End If

'init tag ordering
premTag = d4tag(DB, "PREM_NUM")
d4tagSelect DB, premTag

'init field pointers
fldptr(1) = d4field(DB, "counter")
fldptr(2) = d4field(DB, "filename")
fldptr(3) = d4field(DB, "prem_no")
fldptr(4) = d4field(DB, "hse_range")
fldptr(5) = d4field(DB, "street")

'init field types
InitFldPtrs

CurrRecCount = d4recCount(DB) - 1

frmServUpd.lblMsg1.Visible = False
frmServUpd.MousePointer = 0

'begin update loop
PreLoadUpdates

End Sub
---------------------------------

Any help would be appreciated.

help!!!