[libusb] libusb incompatibility

[manas m. <man...@re...>]

Hi,
 I'm using libusb along with pyusb to access the windows xp usb backend. So far my program worked fine till I installed newer versions in a difference machine on and from January 2015. The code is python to communicate with a cypress usb chip. 
The relevant part of the code is 
-------------import usb.core
import usb.util
import usb.backend.libusb0 as libusb01
import sys
import time
import ddsbackendbk = libusb01.get_backend()
self.ddslist = usb.core.find(idVendor=0x04B4, idProduct=0x1236, backend = bk, find_all=True)

# was it found?
if self.ddslist is None:
    raise ValueError('DDS devices not found')  ------------- It doesn't show the device giving the following massage:
__init__ is calledTraceback (most recent call last):  File "C:/Users/cqtwmanas/Desktop/experiment_control/experiment/src/DDS/ddsmain.py", line 323, in <module>    myapp = MyForm()  File "C:/Users/cqtwmanas/Desktop/experiment_control/experiment/src/DDS/ddsmain.py", line 28, in __init__    self.dds_list = dds.DDS_list()  File "C:\Users\cqtwmanas\Desktop\experiment_control\experiment\src\DDS\dds.py", line 149, in __init__    self.ddsnum = len(self.ddslist)TypeError: object of type 'generator' has no len()-------------------------
Any help in this regard is appriciated.
best regardsMM