I am trying to implement Apple Push Notification using python and django.
i am using following library to implement it
http://leepa.github.com/django-iphone-
I had the exact same problem. Turns out it was a simple error - I had a mistake in IPHONE_SANDBOX_APN_PUSH_CERT and python could not locate my certificate. Once I pointed it to the right location, it started working.
Note that you might want to double-check your certificate first using openssl command line, such as:
openssl x509 -text -in cert.pem
That will give you textual information about your certificate, its validity, etc.
Also, double-check file permissions of the certificate file (the python process must have sufficient rights to access it).