Microsoft Jet problem

I am now using Microsoft Jet 3.5 to access Oracle database. In oracle sqlplus the update SQL is correct, but when committed, an error occurred. This time i use Microsoft Jet 3.5 to catch this error, but i cannot handle it. the error is not raised.
The code is as followed.
Sub update()
Dim dbConnect As Database
Dim wk As Workspace
Dim str As String

Set wk = DBEngine.Workspaces(0)
Set dbConnect = OpenDatabase("wsdm_new", dbDriverNoPrompt, False, Connect:="ODBC;DSN=;UID=user;PWD=pass;")
str = "update emp set name='user1' where id=1"

On Error GoTo PRG_ERR
call DBEngine.SetOption(dbUserCommitSync, "no")
wk.BeginTrans
Call dbConnect.Execute(str, dbSQLPassThrough)
wk.CommitTrans

PRG_ERR:
str = ""
If Errors.Count > 0 Then
For Each sqlErr In Errors
With sqlErr
str = str & .Number & " " & .Description & Chr(10) & Chr(13)
End With
Next sqlErr
MsgBox str
End If
dbConnect.Close
Set dnconnect = Nothing
End Sub

The 'Errors.Count' is 0 when update sql did not run correctly.