there is a problem with the demo"sd_card_audio"

hi,

when i do the demo "DE2_SD_Card_Audio" ,i fellow the steps like below，my quartus version is 6.1

Running the Design

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1) Launch the Quartus II 6.1 software.

2) Open the DE2_SD_Card_Audio.qpf project located in the <install path>\DE2_SD_Card_Audio folder. (File menu -> Open Project)

3) Open the Programmer window. (Tools menu -> Programmer)

4) The DE2_SD_Card_Audio.pof programming file should be listed.

Check the 'Program/Configure' box and set up the ASP programming hardware connection via the 'Hardware Setup' button.

5) Press 'Start' to start programming. The design should now be programmed.

6) Launch the Nios II IDE.

7) Switch the workspace to the <install path>\DE2_SD_Card_Audio folder.

8) Build the project. (Project menu -> Build All)

9) Run the project on the board. (Run menu)

there is a problem when i do the setp 8). the nios II ide said

make -s all

make: *** No rule to make target `C:/DE2/DE2_SD_Card_Audio/system_0.ptf', needed by `C:/DE2/DE2_demonstrations/DE2_SD_Card_Audio/hello_led_0_syslib/Debug/system_description/../obj/generated_app.mk-t'. Stop.

Build completed in 1.156 seconds