Why is the fiber inspection probe for the AQ6380 not connecting?

The AQ6380 fiber inspection probe needs to be plugged into the bottom USB port.

AQ6380 OSA: 5 pm (0.624 GHz) high wavelength resolution, ±5 pm accuracy, 65 dB wide close-in dynamic range, 80 dB high stray light suppression

Measures the power intensity of light across different wavelengths in the electromagnetic spectrum.