Diagnosis
You are trying to create a subscription for example in theAdministration Console. This error occurs if you selected a publicationof type bulk or simple bulk or an intelligent or simple intelligentpublication without criteria fields. For publications of the mentionedtypes it makes no sense to have more than one subscription.

Procedure
If you are not in the Administration Console call it using transactionSMOEAC.
Use the value help for Object type to select Subscriptions
.
Select the in the short text mentioned subscription by doubleclick.
Change to edit mode and assign sites.
Save your changes.