Arduino Nano mini B USB cable Not detected at all in device manager

Hey all,

I've got two borads seeeduino and Arduino nano v3.0. Both need Mini USB to USB cable. I used to have one which works fine for both I just plug it in and I get the device under the COM ports in device manager. Now I need to work with my two borads at the same time so I purshased a new first cable. When I plug it in to nano or seeeduino the power led blnks once then it turns off. So I bought another cable, now when I plug this one the board is powered howerver the rx tx leds don't blink when it gets powered and the board is not detected at all anywhere in the device manager. I can get that the two cables are not ok but I need to know why? I want to get a new one but tired of having useless cables! any ideas? Could my cables work maybe?