error with(hpc) DQ pin while compilation(fitter)

Hi,

I am using quartus ii 9.0. I have instantiated ddr2 hpc and i am using native interface. when i compile the design i am getting the error as

Error: Can't place DQ I/O Pin " ddr_dq[7]" in location PIN_E6--can't place the associated DQS I/O pin "ddr_dqs[0]" in location that feeds this location.

And I am using startix ii FPGA.

Regards

Aravind