In the Quartus® II software version 10.0, the Flow Summary report shows the line DSP block 9-bit elements as N/A until Partition Merge even after the design is fully compiled, when you target Stratix® V devices. DSP block usage is not displayed because Stratix V devices do not have DSP 9-bit elements.
You can check the DSP block usage in the line DSP Blocks of the Flow Summary report.
This problem is scheduled to be fixed in a future version of the Quartus II software.