open-drain option for differential I/O pin

[Altera_Forum]

Hi  

 I have downloaded a reference design (PCIe to External Memory) for arria ii gx. I am trying to reinstantiate and regenerate and recompile the design. However, it fails during fitting. The errors are as belows:  Error: Can't turn on open-drain option for differential I/O pin mem_dqs[1] Error: Can't turn on open-drain option for differential I/O pin mem_dqsn[1]   I can't anything in the design related to open drain. Any clue?   Thanks

[Altera_Forum]

Did u run the pin assignment tcl script?

[Altera_Forum]

I do run the script. After running the script, my .qsf is different from the .qsf of reference design. The error still exists. 

 Currently what i do is i copy assignment in the .qsf of reference design to my .qsf.

[Altera_Forum]

the script might not run successfully. you may check if there is any error msg from the tcl console in quartus.