NXT Ratings can be customized for Custom Ratings, but only 150 active rating categories can be included. 
If you receive this message please do the following to correct the problem.

1. login to The Raiser's Edge database view
2. go to Config>Tables>Ratings
3. Open each Rating entry that is not needed in NXT and mark it as Inactive and click OK
4. Repeat until the total number of Ratings is less than 150

**NOTE: NXT Ratings cannot be opened or marked as Inactive.  This ONLY applies to Custom Ratings.

This information is visible in the NXT Help file as well.