求助：一个非常难的串口方面的小问题

我做了个打开关闭串口的小程序，在win2000系统下，这个程序可以打开和关闭串口，但是到了win98系统下却老是弹出“无法打开串口”对话框,这是怎么回事啊？Createfile这个API函数在win98下应该也可以用的啊，程序在下面，请高手给我指教，谢谢！EMail:jiechen111@163.com

Private sub command1_Click( )
Const GENERIC_READ=&H80000000
    Const GENERIC_WRITE=&H40000000
    Const OPEN_EXISTING=3
    Const FILE_ATTRIBUTE_NORMAL=&H80
    Dim SecurityA As SECURITY_ATTRIBUTES


Dim Temp(5) As String
select case(temp(3))
  Case 0:hCom=CreateFile("COM1",GENERIC_READ OR GENERIC_WRITE,0,SECURITYA,OPEN_EXISTING,FILE_ATTRIZBUTE_NORMAL,0)
  Case 1:hCom=CreateFile("COM2",GENERIC_READ OR GENERIC_WRITE,0,SECURITYA,OPEN_EXISTING,FILE_ATTRIZBUTE_NORMAL,0)
  Case 2:hCom=CreateFile("COM3",GENERIC_READ OR GENERIC_WRITE,0,SECURITYA,OPEN_EXISTING,FILE_ATTRIZBUTE_NORMAL,0)
  Case 3:hCom=CreateFile("COM4",GENERIC_READ OR GENERIC_WRITE,0,SECURITYA,OPEN_EXISTING,FILE_ATTRIZBUTE_NORMAL,0)
  Case 4:hCom=CreateFile("COM5",GENERIC_READ OR GENERIC_WRITE,0,SECURITYA,OPEN_EXISTING,FILE_ATTRIZBUTE_NORMAL,0)
  Case 5:hCom=CreateFile("COM6",GENERIC_READ OR GENERIC_WRITE,0,SECURITYA,OPEN_EXISTING,FILE_ATTRIZBUTE_NORMAL,0)
 Case 6:hCom=CreateFile("COM7",GENERIC_READ OR GENERIC_WRITE,0,SECURITYA,OPEN_EXISTING,FILE_ATTRIZBUTE_NORMAL,0)
 Case 7:hCom=CreateFile("COM8",GENERIC_READ OR GENERIC_WRITE,0,SECURITYA,OPEN_EXISTING,FILE_ATTRIZBUTE_NORMAL,0)
 Case 8:hCom=CreateFile("COM9",GENERIC_READ OR GENERIC_WRITE,0,SECURITYA,OPEN_EXISTING,FILE_ATTRIZBUTE_NORMAL,0)
 Case 9:hCom=CreateFile("COM10",GENERIC_READ OR GENERIC_WRITE,0,SECURITYA,OPEN_EXISTING,FILE_ATTRIZBUTE_NORMAL,0)
 Case 10:hCom=CreateFile("COM11",GENERIC_READ OR GENERIC_WRITE,0,SECURITYA,OPEN_EXISTING,FILE_ATTRIZBUTE_NORMAL,0)
 Case 11:hCom=CreateFile("COM12",GENERIC_READ OR GENERIC_WRITE,0,SECURITYA,OPEN_EXISTING,FILE_ATTRIZBUTE_NORMAL,0)
 end select
 if hcom=-1 then
    i=MSGBOX("无法打开串口",vbOKONLY,"错误")
    End if
End sub

Private sub command2_Click( )
CloseHandle(hcom)
End sub

module里声明如下：
Public Declare Function Createfile lib "kernel32"Alias"CreateFileA"(Byval lpFileName As String,Byval dwdesiredAcess as Long ,Byval DwshareMode As Long ,LpsecurityAttribute As Long , Byval DwFlagsandAttributes As Long ,Byval HtTemplateFile As long)as Long

Public Declare Function CloseHandle lib "kernel32"(ByVal hobject As long)as long