Using SIM with mobile wifi device

I have a Vodafone mobile wifi device. Worked ok with Vodafone SIM and with Giffgaff SIM. Tried a Lebara unlimited data SIM and it doesn’t work. Anybody knows why not?

Lebara SIMs work just like those from other networks so there shouldn't be any issues. Just to confirm, was the SIM been properly activated before you put it into the wifi device?

Martin I've got the same problem and I've activated the SIM on my iPhone