How old is your tank? You really should wait about a year to add a nem...
Anyway, nems go where they want. You can try adjusting the light and/or flow in the tank to get it to move. The nem may not host the clowns. I have tried a few times and the first two times the clowns totally ignored the nem. This last time they took to it almost right away and now bring food to it and keep the area clean. It is a cool thing to watch, but I just want to make you aware there is a good chance they might not even host.
Good luck!