What EXOS switch is this, and what version of EXOS is it running?
Support for policy was added to EXOS in 16.1.1.4. It is supported on the X450-G2, X460-G2, X670-G2, and X770. Netsight must also be version 6.2.0.221 or higher for Policy support on EXOS switches.
You can find more information one what switches support Policy in the following GTAC Knowledge article:
What EXOS based switches support Policy manager?
-Brandon