every now and again you buy a piece of hardware designed by a new engineer that dosent know about the standard for power plugs and puts 5v on the outside and gnd on the in, so that every charging device is incompatible with it.
for me it was a iomega 60G usb hard drive that has the plug connected the wrong way around yet it uses the same connector as my Z, meaning that all my battery packs are incompatible with it
anyway back on topic, try getting one of these:http://www.targus.com/us/product_details.asp?sku=PAUH212Uhttp://www.targus.com/us/product_details.asp?sku=ACH74US
or if you can (because its as large as a CF card):http://www.targus.com/us/product_details.asp?sku=ACH63US
note that targus is not the only maker of these products, i have bought no nome brands that were exactlly the same