VBA application Ontime - vba

Question

I got some problem with application.ontime maybe somebody knows the solution
From the beggining
Private Sub Workbook_Open()
'some code
call macro_name
end sub
sub macro_name
'some code refreshing data on form
call start_timer
end sub
dim start_time as date
Sub start_timer()
start_time = Now() + TimeValue("00:00:05")
Application.OnTime start_time, "macro_name"
End Sub
Sub end_timer()
Application.OnTime start_time, "macro_name", , False
'MsgBox "done" i put this to be sure that code is executed
End Sub
Private Sub Workbook_BeforeClose(cancel As Boolean)
'some code
call end_timer
end sub
problem is that the timer doesn't stop. If i have some other workbook open and i close the one with ontime code it starts again at scheduled time
if i put buttons on a form
Private Sub CommandButton1_Click()
start_timer
End Sub
Private Sub CommandButton2_Click()
end_timer
End Sub
everything works ok and ontime is canceled.
I solved it partly by putting the
call end_timer
on the form closing button
Private Sub Image1_Click()
end_timer
ThisWorkbook.Close
End Sub
but if workbook will be closed some other way than button ontime won't be canceled
sorry for my english i'll try to explain better if something is unclear