Impossible read and write. I only get the UID

[ingeniapp]

Hi
I'm trying to read and write a mifare classic card with default keys and alwyis get a value error (-2) on each authenticate.
I only get the UID. The ouput when I type ' python mifareauth.py' is
Reading card 4ec6f455
0
1
2
...

Others apps as 'nfc-mfclassic w a u outputp.mfd' write and read fine.

What is wrong in my pynfc installation?

Thanks in advance

[jtrip]

Out of curiosity how did you go about installing pynfc?