**ERROR: (ENCLF-53): " The layer 'VTL' is not found in the database.
A layer must be defined before it can be referenced."
You faced this error because the layer "VTL" is not defined into the "function" section of your techfile. You need to define the function of this layer which in your case should be defined as 'nimplant' or 'pimplant'.
**ERROR: (ENCLF-268): " There is no spacing table defined bewteen cut class
'square' and 'square' in layer 'VIA6'. It may cause certain commands not working"
Please make sure you techfile contains the spacing information for the square to square cutclass spacing.
You use the right command to export technology information from Virtuoso but maybe your techfile does not contain all required information.