USB-Blaster 2.6 kernel problem

I had similar problem on Fedora core 6, which use udev too.

$ jtagconfig
1) USB_Blaster 
  Unable to lock chain (Insufficient port permissions)

I changed the mode to "0666" but still have the same error.

ACTION=="add", SUBSYSTEM=="usb_device", 
        PROGRAM="/bin/sh -c 'K=%k; K=$${K#usbdev}; printf bus/usb/%%03i/%%03i $${K%%%%.*} $${K#*.}'", 
        NAME="%c", MODE="0644"

Strangely, after some tries it worked once or twice, but failed later. I think jtagd did not get correct device. And jtagconfig can not handle the "add".