Cambridge 851n won’t connect to hard drive

Just purchased this 851n. (I hope it wasn’t a mistake.) I cannot get it to see the music on my hard drives. The drive I wanted to use is a Western Digital SSD drive. I’ve also tried a MicroSSD drive and my Iphone. Nothing... I’ve tried resetting the unit and it still does not recognize any music. 
...All of the above work just fine on my pc and car.
Any help would be appreciated.
Thanks