Unable to Add T-Mobile 4G Mobile Hotspot Network

I have a Nexus 7 tablet with internet from a T-Mobile 4G hotspot via wireless connection. When I connect to the Sandisk Wireless Flash Drive (running latest firmware), it is unable to discover the hotspot. Without the flash drive, the hotspot works. The flash drive is able to discover my house wireless network and supply internet that way, but not with the T-Mobile.

Suggestions or is this a known issue?