Issues with receiver(wireless) using mobile internet

Hi,
I am using an optibox evo e3 hd with a wireless usb stick. It was working perfectly when connected to a virgin router wirelessly. However when i try to connect to mobile internet/wi-fi hotspot, it does not connect. When i look at the wlan status it momentarily shows it can see the network and then drops it and shows there is no connection. Is there a setting i need to play with or change?
Thanks

Hi. Thanks for the reply. The hot spot belongs to me as i have mobile wifi on the three network. After tinkering it can now pick the hotspot and i have assigned a manual ip address but when i run the network test this is what i get:
Lan adapter: wlan connection ok(green)
wireless network: ok
dhcp: disabled
ip address : unconfirmed
nameserver: unconfirmed

Sorted by reflashing the receiver. Thanks for your help.