带有LPCTSTR类型参数API函数怎么调用

带有LPCTSTR类型参数API函数如何调用
DLL帮助文档中的函数说明如下
 RC WINAPI LJIF_SaveEnvironmentFile(IN LPCTSTR szFilePath)  
  
 Description: Reads the environment setting file from the controller and saves it with the specified name.  
 Parameter:szFilePath (Setting file name *Specify the full path. )
 Returned value :0x00 (Completed without errors  
  Other See "Return Code List" )
 Remarks The controller must be set to communication mode.  

现在准备用VB中的Commondialog 获取地址传递给 API函数
相应程序如下：

声明
Global sSourcePgm$
Global sDestFile$

 Declare Function LJIF_LoadEnvironmentFile Lib "LJIF.dll" (ByVal szFilePath As Long) As Long
 Declare Function LJIF_SaveEnvironmentFile Lib "LJIF.dll" (ByVal szFilePath As Long) As Long

调用过程
Private Sub LoadEnvironment_Click()
  On Error Resume Next
  With Dlg
  .FileName = sSourcePgm
  .CancelError = True
  .DialogTitle = "请根据探头型号选择配置文件"
  .Filter = "Lg environment setting file (*.env)|*.env|All files|*.*"
  .Action = 1
  If Err Then
  Err.Clear
  Exit Sub
  End If
  sSourcePgm = .FileName
  szFilePath = VarPtr(sSourcePgm)
  End With

  Re = LJIF_LoadEnvironmentFile(szFilePath)
  Call ReturnCode
  If Re = 0 Then
  StatusBar1.Panels(2).Text = "环境设置完成"
  Else
  StatusBar1.Panels(2).Text = "环境设置失败"
  End If
  
End Sub

在调试中，发现返回参数不正常，不能确执行。请各位高手帮忙看看哪里错了，指点一二。


[解决办法]

VB code

dim sFilePath as stringsFilePath =string(255," ")Re = LJIF_SaveEnvironmentFile(sFilePath)
[解决办法]
直接用字符串调用
VB code
(ByVal szFilePath As String)
[解决办法]
LJIF_LoadEnvironmentFile StrPtr(.FileName)
或者
LJIF_LoadEnvironmentFile StrPtr(StrConv(.FileName, vbUnicode))

看看