Topic: libnfc + ACS ACR122U PICC Interface

Hi everyone!
I have just installed libnfc and I'm trying to use nfc-tools.
After about two hours of work, I ended up in this situation:
- I have installed libnfc
- modified the source code with the help of a topic here libnfc.org/community/topic/1029/cardreader-acr-1222u-and-libnfc/
- now when I run

 sudo nfc-list -v 

I see something like this:

 
MacBook-Pro-di-Marco-3:libnfc-1.7.1 Marco$ sudo nfc-list -v
nfc-list uses libnfc 1.7.1
error    libnfc.driver.acr122_usb    Unable to claim USB interface (Permission denied)
nfc-list: ERROR: Unable to open NFC device: acr122_usb:250:006
error    libnfc.driver.acr122_usb    Unable to claim USB interface (Permission denied)
nfc-list: ERROR: Unable to open NFC device: acr122_usb:250:006
NFC device: ACS ACR122U PICC Interface 00 00 / ACR122U214 opened
1 ISO14443A passive target(s) found:
ISO/IEC 14443A (106 kbps) target:
    ATQA (SENS_RES): 00  04  
* UID size: single
* bit frame anticollision supported
       UID (NFCID1): d5  27  9a  dd  
      SAK (SEL_RES): 08  
* Not compliant with ISO/IEC 14443-4
* Not compliant with ISO/IEC 18092

Fingerprinting based on MIFARE type Identification Procedure:
* MIFARE Classic 1K
* MIFARE Plus (4 Byte UID or 4 Byte RID) 2K, Security level 1
* SmartMX with MIFARE 1K emulation
Other possible matches based on ATQA & SAK values:

0 Felica (212 kbps) passive target(s) found.

0 Felica (424 kbps) passive target(s) found.

0 ISO14443B passive target(s) found.

0 ISO14443B' passive target(s) found.

0 ISO14443B-2 ST SRx passive target(s) found.

0 ISO14443B-2 ASK CTx passive target(s) found.

0 Jewel passive target(s) found.

As you can see, the software can open my nfc card (as you can see from this piece of the previous code):

NFC device: ACS ACR122U PICC Interface 00 00 / ACR122U214 opened
1 ISO14443A passive target(s) found:
ISO/IEC 14443A (106 kbps) target:
    ATQA (SENS_RES): 00  04  
* UID size: single
* bit frame anticollision supported
       UID (NFCID1): d5  27  9a  dd  
      SAK (SEL_RES): 08  
* Not compliant with ISO/IEC 14443-4
* Not compliant with ISO/IEC 18092

Fingerprinting based on MIFARE type Identification Procedure:
* MIFARE Classic 1K
* MIFARE Plus (4 Byte UID or 4 Byte RID) 2K, Security level 1
* SmartMX with MIFARE 1K emulation
Other possible matches based on ATQA & SAK values:

0 Felica (212 kbps) passive target(s) found.

0 Felica (424 kbps) passive target(s) found.

0 ISO14443B passive target(s) found.

0 ISO14443B' passive target(s) found.

0 ISO14443B-2 ST SRx passive target(s) found.

0 ISO14443B-2 ASK CTx passive target(s) found.

0 Jewel passive target(s) found.

But something goes wrong at the beginning of the process:

nfc-list uses libnfc 1.7.1
error    libnfc.driver.acr122_usb    Unable to claim USB interface (Permission denied)
nfc-list: ERROR: Unable to open NFC device: acr122_usb:250:006
error    libnfc.driver.acr122_usb    Unable to claim USB interface (Permission denied)
nfc-list: ERROR: Unable to open NFC device: acr122_usb:250:006

also, when I try to

sudo nfc-scan-devices-v 

I obtain:

 MacBook-Pro-di-Marco-3:libnfc-1.7.1 Marco$ sudo nfc-scan-device
nfc-scan-device uses libnfc 1.7.1
3 NFC device(s) found:
error    libnfc.driver.acr122_usb    Unable to claim USB interface (Permission denied)
nfc_open failed for acr122_usb:250:006
error    libnfc.driver.acr122_usb    Unable to claim USB interface (Permission denied)
nfc_open failed for acr122_usb:250:006
- ACS ACR122U PICC Interface 00 00 / ACR122U214:
    acr122_pcsc:ACS ACR122U PICC Interface 00 00 

what is the problem here?
My setup is: Mac OS X 10.9.5 , ACS ACR122U-A9 with usb driver.

Have a nice day smile