Oscillating Plate with two way FSI
 

Hello Gals and Guys,
I am attempting the tutuorial in chapter 23 in cfx tutorials titled "Oscillating Plate with two way FSI". I am using ansys work bench 14.5. At page 457, while creating fluid solid external boundary named interface
" In the boundary details tab, Mesh Motion, the ansys interface option does not appear. So i am not able to select FSIN_1".
Please somebody help me.