Unable to query target part layout

Unable to query target part layout!!!

When I work with the xilinx edk(ver8.1), after buttoning down the �
download bitstream�, I want to make a bootloader from the external flash
,but a problem still baffles me all the time, when I pressed the �program
flash memory�, here is the context showed to me..
-------------

Performing CFI Query on the flash part(s)...Processor started. Type
"stop"
to stop processor
XMD% ERROR: Flashwriter application reported an error: Unable to query
target part layout!
Processor started. Type "stop" to stop processor
Flashwriter terminating !

Done!


What causes this problem? And What should I do to solve the problem? 
The flash I use is AM29LV040B-70JC. 

> XMD% ERROR: Flashwriter application reported an error: Unable to query
> target part layout!

One possible cause of this is the data cache. Make sure the data cache
is disabled for the memory range of the flash. (It seems to me
flashwriter ought to do this automatically, but it does not...)

HTH
Steve