JTAG stop working

I don't know why the JTAG stoped working ... I'm using Microtronix's Cyclone EP1C20.

When I try to upload to the board, I got these messages :

- inside Nios SDK 5.0.1 Build: 86, uploading the kernel :

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Microtronix Linux Extensions

Version 1.4, Built June 20, 2005

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06/09/2005 20:44:05 - (INFO) nios2-flash-programmer: Launching Quartus Programmer to download:

D:/Programas/Altera/Nios/components/altera_nios_dev_board_cyclone_1c20/system/altera_nios_dev_board_cyclone_1c20.sof

Error: Can't scan JTAG chain. Error code 87.

06/09/2005 20:44:06 - (SEVERE) nios2-flash-programmer: Unable to download SOF: D:/Programas/Altera/Nios/components/altera_nios_dev_board_cyclone_1c20/system/altera_nios_dev_board_cyclone_1c20.sof, exiting

I have tryed to auto-detect the hardware in the Quartus II Programmer, and it say to me :

Unable to scan device chain. Can't scan JTAG chain.

I dont remember where these showed up too:

Error: Can't access JTAG chain

Error: Operation failed

I dont know what to do. I have tryed to set the jumpers back to the default, as is in Cyclone Data Sheet. Everything seems normal. I can not upload the Kitchen_sink core, because the erros of JTAG http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/smile.gif , so I can&#39;t test it.

Any suggestions ??

Regards.

Arthur.