Due to a problem in the Quartus® II software version 12.1, you may see the options for Netlist to export are turned off and unavailable and get an error when you try to generate a Quartus II Exported Partition File (.qxp).
To work around this problem, right-click on the partition you want to export in the Project Navigator pane and point to Design Partition and then click Export Design Partition.
This problem is scheduled to be fixed in a future release of the Quartus II software.