When adding assignments to multiple Gradebooks at once, the Assignment type must be already included in all of the Gradebooks. If you are getting an error, double check your Gradebook setup for all sections and make sure the assignment type you selected is included.

In order to do this open the Gradebooks and follow these steps:
  1. Click Edit Setup
  2. Click the Select Assignment Types button
  3. Select the Assignment type(s) to add
  4. Click save
Once the Assignment type is in all Gradebooks, you should be able to add your assignment to the gradebooks.