Troubleshooting QVE errors by reviewing messages in the Results panel in QlikView Expressor Desktop may require you to scroll to capture the real error. It can be difficult to discern what is an actual error causing the Dataflow to fail versus what constraint rule(s) is/are begin violated and then displayed when using constraints in your Semantic Type. Incoming data values that violate semantic constraint rules will be displayed in the Results panel output along with any real fatal errors. This is controlled by using the Show errors: check box in the properties panel for a particular operator.
Fig. 1 - Reading a QlikView QVX file using the Read QlikView Operator - Show errors is checked
Fig. 2 - The semantic constraint ONLY allows values of the string "qvw" for the Extension attribute to be processed, the rest will be rejected.
Fig. 3 - The Results panel by default displays constraint error violations and the values of those that violate the constraint for the attirbute "Extension"
As you can see, this may make it difficult to identify the "true" cause of the fatal error. Simply turn off Show errors: for the operator to eliminate the extra messages in the Results panel.
Fig. 4 - The real fatal error is now easier to see - "attempt to index global input (a nil value)