Can't upload programs to nano with Mac

I got 4 Arduino nano and they were put into the same circuit, individually. Then everything went to crazy and it wasted me hole day to find what's wrong with these shit.

  1. the nano can't get power supply from usb port and I don't know why (the nano can be recognised by Mac);

  2. I use an USB adaptor to provide power via port Vin;

  3. I've already installed the FTDI driver BUT IT TOTALLY DOESN'T WORK!

  4. hence I have to find other drivers to solve the problem;

  5. now I can use a cu.* port to upload my programs to three of my nano;

  6. the remained one made me crazy cause it says "programmer is not responding";

  7. reset is unavailable before uploading, or it will say that "device not configured";

  8. I'm working with OS 10.9.5 Mavericks;

Could anyone help me to figure out what happens to the weird nano? Thanks a lot!

This happens to me on Windows 7 too, even down to the "programmer is not responding". I have no idea what causes it, but I would like t find out.