Function GetLeftBackStr(bigstr As String, keystr As String) As String
	On Error Goto FErrorHandler
	Dim pos As Integer
	pos = Instr(1, bigstr, keystr, 5)
	If (pos>0) Then
		' use StrRightBack to get substring
		GetLeftBackStr = Strleftback ( bigstr, keystr, 5, 1 )
	Else
		' return original string
		GetLeftBackStr=bigstr
	End If
	
	Exit Function
FErrorHandler:
	GetLeftBackStr=bigstr
	Exit Function
End Function