Error compiling the standard niosII_cycloneII_2C35

[Altera_Forum]

when I compile the standard.qpf of cycloneII_2C35 using Quartus 9.0, it geneated an error: 

error: node instance "ddr_control" instantiates undefined entity "auk_ddr_controller".  what can i do to solve this problem,i try to remove the db directory but the error doesn't disappear:confused::confused: 

[Altera_Forum]

you'll probably have to regenerate all of the cores including the DDR controller in 9.0 since the design was built in an earlier version of the software. just open each core in the MegaWizard, and generate. 

 note that you might run into problems with change in interfaces or behavior of the cores between versions, so there might be some debugging ahead. you might want to install the version in which the designs were created to confirm functionality, then start working in the newest version of the software for your own projects.

[Altera_Forum]

I solved this problem by removing the db,ddr_sdram_controller-library,incremental_db,software_examples,testbench directories and then generating the sopc builder then compiling the standard. 

 I haven't any error again:):cool:;)