It gets a little difficult to "guess" the factors we are dealing with in this situation, but I will try to help with the little experience I had with ADB + Mac OS. Below are some questions that may help diagnose the problem; I will edit the answer according to future information:
Checklist of the Situation
(1) What version of Mac OS are you using? 10.6 (Snow Leopard), 10.7 (Lion), 10.8 (ML), 10.9 (Mavericks) or 10.10 (Yosemite)? Or none of them? (Maybe an older one.)
(2) Did you mention Eclipse - I believe you downloaded the Android SDK and have access to all the latest tools?
(3) When you say that "...I’m trying to activate Debugger mode...", you are stating that you have already unlocked the Developer Mode playing fast (7-8 times ) on the Build Number in "Settings > About your phone"? (Assuming the latest versions of Android, may vary according to manufacturer and version.).
(4) What version of OS do you have on your mobile? 4.1, 4.2, 4.3, 4.4? Is it stock or you carried a custom ROM? If it is stock, you took access root?
(5) If we are a custom ROM, you’re sure it’s working as it should? I’ve had cases where I "made fun" so much the device, I had to make a Factory reset to return to debug as it should.
(6) Once checked all the above steps, you came to test on another machine, preferably with another operating system (with its proper drivers installed. ) as Linux or Windows? Mac OS doesn’t need drivers to run ADB on most Androids (at least not the ones I tested - Samsungs Galaxy S2-S4, Moto E/G/X)
A little bit of "Troubleshooting"
Now, let’s try to deal with the problem.
ADB and Privileges
The adb-server is started the first time you execute the command ./adb devices, because it needs a communication interface (e. g. "daemon") to listen in a random port and establish communication with the OS on the mobile. This daemon need privileges to write via USB and because it is a system based on UNIX, Perhaps your problem might be running the adb from a non-privileged location/user. Try running sudo ./adb devices to delete the possibility of being a problem due to lack of privileges. - If daemon is already being executed, first of all, mate the process with a kill [PID]where [PID] is the process identifier. You can find this out with something as simple as ps aux | grep adb. (If by any chance the process stalls and not "die", try kill -9 [PID].
Hardware > Software > Environment Change
Another possible failure in this communication can be, Ionically, the cable. Test with another USB cable to make sure that this is not the problem. Or even, in this same line, try to mount the USB share on your device and transfer some file via Android File Transfer, a client developed precisely for this - transfer Android files to Mac. If you can make that transfer, then your cable and communication are OK.
If your hardware check shows no problems and there are no obvious reasons why the software doesn’t "chat" properly, try the step (6) Checklist. Try another system and see if everything works well. You can use something like 15 sec. ADB Installer to prepare a Windows machine in a matter of seconds to perform its test. Without having to download the whole SDK again.
If the Android File Transfer, as mentioned above, function normally but the adb continue not seeing your device, you have one of two problems:
(1) Your phone is unable to emulate USB debugging
(2) Your libraries/kexts on OS X are somehow messy
Anyway, it will only be possible to help in addition, with more information. I hope to have helped in some way.
To USB debugging your device development options are already enabled?
– Paulo Rodrigues
There is a file: . android/adb_usb.ini, you may need to add the USB vendor id to this list
– Marabita