DFRduino Nano not connecting via USB

Hi guys,

i have two DFRduino Nano's that i have just recently purchased...ive used other nanos before these.

the problem i have is that these nano's dont appear as a registered device in device manager in windows 7.

ive looked around the net for any drivers for these but i can find anything.

ive installed the 'CDM v2.12.00 WHQL Certified' drivers, but again have had no luck with my laptop recognizing these nanos.

i can plug in another other nano or other arduino device and its gets recognized.

im not lost for ideas as to way i cant get these to communicate with my PC.

anyone got any thoughts on why this is the case????

David