error:variable not defined?????

[junlo]

Private Sub mnuFileMRU_Click(index As Integer)

    strFileNewName1 = (Left(mnuFileMRU(index).Caption, InStr(1, mnuFileMRU(index).Caption, "\DAF")) & "Map\")
    strFileNewName2 = (Mid(mnuFileMRU(index).Caption, InStr(1, mnuFileMRU(index).Caption, "MY"), 8) & ".bmp")
    strFileNewName3 = strFileNewName1 & strFileNewName2
    'MsgBox " " & strFileNewName3
    
    Picture1.Picture = LoadPicture(strFileNewName3)
    
   Call ConvertMRU
   End Sub

Private Sub ConvertMRU()

    Dim intFF As Integer
    Dim strReaded() As String
    Dim index as integer    
       intFF = FreeFile
       
            Open mnuFileMRU(index).Caption For Input As #intFF
                strReaded = Split(Input(LOF(intFF), #intFF), vbLf)
           Close #intFF
         
         strFileNewName4 = (Left(mnuFileMRU(index).Caption, InStr(1, mnuFileMRU(index).Caption, "\DAF")) & "Setting\Daf.txt")
         'MsgBox "" & strFileNewName4
         
        intFF = FreeFile
            Open strFileNewName4 For Output As #intFF
                Print #intFF, Join(strReaded, vbCrLf);
            Close #intFF

End Sub

above is part of my code. it came out an error "variable not defined" and point to index(the red color). how to improve the code above?