Digilent JTAG USB Cable and chipscope

[Ummar]

hi every one
i am a newbie and i have a problem with the chipscope.
i am using "Digilent JTAG USB Cable"
http://www.digilentinc.com/Products/Detail.cfm?NavPath=2,395,523&Prod=JTAG-USB
problem is that during debugging i cannot observe any signal names (from my program) in chipscope.

no waveform is observed only lines are shown

although i can observe some signal changes, but transition state (edges) are never shown.

for example if a signal was zero then a line appears with low state when it is one the same line
appears with high state, no transition observed. the clock oscillator on my board is also appearing as a straight line.

the features of this cable does not show support for xilinx tools, but some plugins from
digilent site enable me to make this cable work with IMPACT tool. so i can download my
program file to PROM using this cable. but chipscope is not working good

is there some speed issue or this cable is not supporting at all ? but then why signal change is shown ?
also please suggest me any other cheap usb jtag cable that works good with chipscope.

does "Digilent JTAG HS1 Programming Cable" works fine ?
http://www.digilentinc.com/Products/Detail.cfm?NavPath=2,395,922&Prod=JTAG-HS1

eagerly waiting for ur reply