Thanks for writing. How long ago did you receive your bare-root perennials? If it was within two weeks or so, your plants may still be ramping up their growth.
If it's been more than three weeks or so, I'd guess something bad happened. You might carefully dig around one of the ones that doesn't appear to be coming up and take a look. See if the roots are firm and healthy, with new white roots.
---Justin, Senior Garden Editor, BHG.com