The way I fixed this was to add a Domain Calculator node. The clue here is the part of the message that says the “domain of the Label column might not be available” - the node is configured for the domain associated with the 40 rows, not the 134 rows. When the domain changes, the node isn’t sure what to do.
Dear ScottF
Thank you for your correct answer. Thanks to you, I was able to teach the “learner” my entire dataset.
But I had another problem.
For a classifier, the predictions are correct when I give three or less values, while the predictions are wrong when I give more than three values.
I’m not sure I understand what you mean. Can you upload the latest version of your workflow? How do you determine which predictions are incorrect, and how are you scoring the results of your model?