The reader-level validation error is displayed when the Reader in the workbook or workflow canvas is not configured. The error occurs for any of the following:

• No data fields are selected in the Reader in a workbook or workflow.
• If the dataset is modified after the corresponding Reader has run successfully in a workbook or workflow.

To view reader-level validation errors in a workbook, follow the steps given below.

1. Create a Workbook. Refer to Creating a Workbook.
2. From the Task Pane on the left, click Reader.
3. From the Reader drop-down, select the dataset that you want to add to the canvas.
   Here, we select the reader, Iris CSV.
   
4. Drag-and-drop or double-click the dataset to add it to the canvas.
5. Click Save on the Functions Pane.
   The workbook is saved.
6. Click Validate.
   The Validation Errors window is displayed.
   If the dataset does not display any features from the source dataset, the reader-level validation error message is displayed, as shown in the figure below.

   
   Figure: Reader-level Validation Error – Input Variable Not Selected

   When the dataset is modified after the Reader has run successfully, the reader-level validation error message is displayed as shown in the figure below.

   
   Figure: Reader-level Validation Error – Variables Changed

7. Click the Close icon () to return to your workbook canvas.