Two items come to mind;
1 Format the external drive as NTFS
2 Very often laptop usb ports do not have enough pw for an external drive. Does your usb cable use a single or dual end? Does it look like the pic below?
1 Format the external drive as NTFS
2 Very often laptop usb ports do not have enough pw for an external drive. Does your usb cable use a single or dual end? Does it look like the pic below?