Error: Boundaries too far apart
 

1)I am using the sliding mesh method in my modelling. 2)I set the interface boundary condition respectively at the overlaping region where a stator meet a rotor in Gambit, then export to Fluent. 3)When I try to define the interfaces of the stator and rotor to one in Fluent, the error message "Error: Boudaries too far apart" pop out. 4)I checked back the location of these two interfaces in Gambit, they match. 5)Do you know where is going wrong?

Lam