System can't find WinSCPnet.DLL

'===================================================================================================================================
Public Function WinSFTP_Send_CTC(ByVal tcHostName As String, ByVal tcUserName As String, ByVal tcPW As String, _
                                 ByVal SSHKFP As String, ByVal tcSrcDir As String, ByVal tcSrcFileName As String, _
                                 ByVal tcDstDir As String) As Boolean
'===================================================================================================================================
' Purpose       : Transfers files from one place to another using SFTP.
' Description   : .
' Parameters    : .
' Side effects  : None.
' Notes         : 1. Requires full path to the WinCSPNet.DLL in the Project's References subsection.
'                 2. Verbose on error if run in VS's IDE, silent otherwise.
'                 3. No parameters' verification, presumed valid (errs if not, and then see p. 2).
'===================================================================================================================================
Dim llRet As Boolean = True, lcLogStr As String = "", lcErrStr As String = "", loSessionOptions As New SessionOptions, _
    lcDstDir As String = AddBackSlash(tcDstDir)
Dim liWildCardChrCnt As Int16 = GetChrCount("*", tcSrcFileName), lcFullPath2File As String = "", lcJustFName As String
Dim laFiles(0) As String

If liWildCardChrCnt > 0 Then
   laFiles = Directory.GetFiles(tcSrcDir)
Else
   laFiles(0) = AddBackSlash(tcSrcDir) & tcSrcFileName
End If

' Array laFiles[] contains now full path to each of the source files in the source directory

With loSessionOptions
   .Protocol = Protocol.Sftp
   .HostName = tcHostName
   .UserName = tcUserName
   .Password = tcPW
   '.SshHostKeyFingerprint = SSHKFP
   .GiveUpSecurityAndAcceptAnySshHostKey = True
End With

Using loSession As New Session
   Dim loTransferResult As TransferOperationResult, loTransferOptions As New TransferOptions
' Connect
   loSession.Open(loSessionOptions)

   If Not loSession.Opened Then
      llRet = False
      lcLogStr = lcLogStr & Now.ToString("yyyy-MM-dd HH:mm:ss") & ": Session.Open(SessionOptions) failed!" & vbCrLf & Space(21) & _
                 "Program quits." & vbCrLf
      Write2Log(gcLogFile, lcLogStr, True)

      If glDevelop Then
         MsgBox("Session.Open(SessionOptions) failed!" & vbCrLf & "Program quits.", MsgBoxStyle.Critical, "Session Open failed!")
      End If 'glDevelop

      Return llRet
   End If 'Not loSession.Opened

' Upload files
   loTransferOptions.TransferMode = TransferMode.Binary

   Try

      For Each lcFullPath2File In laFiles
         lcJustFName = Path.GetFileName(lcFullPath2File)

         loTransferResult = loSession.PutFiles(lcFullPath2File, lcDstDir & lcJustFName, False, loTransferOptions)

         If Not loTransferResult.IsSuccess Then
            llRet = False
            lcLogStr = lcLogStr & Now.ToString("yyyy-MM-dd HH:mm:ss") & ": transfer of the file" & lcFullPath2File & _
                 vbCrLf & Space(21) & "to " & tcDstDir & " failed!" & vbCrLf & Space(21) & "Program quits." & vbCrLf
            Write2Log(gcLogFile, lcLogStr, True)

            If glDevelop Then
               MsgBox("Transfer of the file " & lcFullPath2File & " to " & tcDstDir & " failed!" & vbCrLf & "Program quits.", _
                     MsgBoxStyle.Critical, "File transfer failed!")
            End If

            Exit For
         End If

      Next

   Catch loErr As Exception
      lcLogStr = lcLogStr & Now.ToString("yyyy-MM-dd HH:mm:ss") & ": ERROR OCCURED while transfering file" & lcFullPath2File & _
                 vbCrLf & Space(21) & "to " & tcDstDir & "!" & vbCrLf & Space(21) & loErr.Message & _
                 vbCrLf & Space(21) & "Occured in " & vbCrLf & Space(21) & loErr.Source & vbCrLf & Space(21) & _
                 loErr.StackTrace & vbCrLf & Space(21) & "Program quits." & vbCrLf
      llRet = False
      Write2Log(gcLogFile, lcLogStr, True)

      If glDevelop Then
         lcErrStr = "ERROR OCCURED!" & vbCrLf & loErr.Message & vbCrLf & "Occured in " & vbCrLf & loErr.Source & vbCrLf & _
                     loErr.StackTrace & vbCrLf & "Program quits."
         MsgBox(lcErrStr, MsgBoxStyle.Critical, gcAppName & ": WinCSP failed!")
      End If

   End Try

   loSession.Close()
   loSession.Dispose()
End Using

Return llRet

End Function
'===================================================================================================================================