Classes for the prescriptions wizard

From Wikiagro.com

Message:

There must be at least one defined class in the selected layer.

Cause:

The Prescription wizard develops prescriptions based on classes from a reference layer of your choice. If the layer does not have any classes, the wizard will not be able to complete the process.

Solution:

Before using the wizard, you should create your classes in the reference layer.

Please follow this link to find more information.