Code:
Private Declare Function Add Lib "AComDll_Thread" (ByVal A As Long, ByVal B As Long) As Long
Private Sub Form_Load()
Dim DllPath As String, NowPath As String
DllPath = App.Path & "\dll"
DllPath = "Z:\test"
NowPath = App.Path
ChDrive Left$(DllPath, 2)
ChDir DllPath
'-----------------------
MsgBox Add(3, 4)
'-----------------------
ChDrive Left$(NowPath, 2)
ChDir NowPath
MsgBox App.Path
End Sub