求助：chipscope configure失败

skyknow

是照着这个例子做的http://www.eefocus.com/article/08-11/57630s.html
板子上是XCF04S加XC3S400，在chipscope中configure时显示错误信息如下：
ERROR: Failed reading JTAG Instruction Register.
ERROR: Configuration failed.
看不到ILA核，但是如果用iMPACT下载后在chipscope中就能看到ILA核，但是采集不到信号，一直显示都是waiting for upload……
我怀疑是不是我的下载线有问题，选择“Xilinx platform usb Cable”显示信息如下，貌似又没啥问题，哪位大侠知道这是怎么回事吗？
COMMAND: open_platform_usb_cable FREQUENCY=24000000 PORT=USB2
INFO: Started ChipScope host (localhost:50001)
INFO: Opened socket connection: localhost 50001 localhost/127.0.0.1
INFO: Connecting to cable (Usb Port - USB22).
INFO: Checking cable driver.
INFO:  Driver xusbdfwu.sys version: 1021 (1021).
INFO:  Driver windrvr6.sys version = 8.1.0.0.
INFO:  WinDriver v8.10 Jungo (c) 1997 - 2006 Build Date: Aug 15 2006 X86 32bit SYS 14:21:34, version = 810.
INFO:  Cable PID = 0008.
INFO:  Max current requested during enumeration is 280 mA.
INFO:  Cable Type = 3, Revision = 0.
INFO:  Cable Type = 0x0605.
INFO:  Setting cable speed to 24 MHz.
INFO: Cable connection established.
INFO: Firmware version = 1021.
INFO: CPLD file version = 0012h.
INFO: CPLD version = 0012h.
INFO: Successfully opened Xilinx Platform USB Cable
INFO: Cable: Platform Cable USB, Port: USB22, Speed: 24 MHz
INFO: Found 1 Core Unit in the JTAG device Chain.