Orange Spotted Ricordea won't attach

[HumanIMDB]

We bought a small Orange Spotted Ricordea on the weekend. We got a deal on it because it had detached from a larger rock that had 4 or 5 larger ones on it; very nice but way too big for our nano and a tad more than we wanted to spend.

We've been keeping it in a glass (low flow and low light) inside the aquarium with a small piece of rock hoping that it will attach to it but it doesn't seem to want to.

Any ideas on how to make coax it to put down roots?

We're afraid that if we take it out of the glass that it will root somewhere we won't be able to see it...