Error Message: could not find the attribute in the DataTableSpec for the test data

So, I am getting the error message cited in the subject when I attempt to apply a simplelogistic predictor against a new set of documents.  How do i solve this problem?

 

Your test data is missing an attribute (column) that was used for training the model. You need to train the model without this column or somehow make sure the test/prediction data contains it.