mmm.. my knowledge of the lacie firmware is limited. So I do not really know what could be the cause :dontknow
But a suggestion, not very likely but you never know. Maybe the firmware thinks the firmware you want to install is older then the one on the box, did you use the right update file ? (was it a newer version then what is installed now ?)
or you need an upgrade to a version between the one installed and the latets one as the newest firmware may not be compatible with the upgrade method of the old firmware
for example read the info on this page
http://manuals.lacie.com/en/manuals/d2- ... rk2/updateSeems you need to do something different if you have 2.0.x or 2.1.x versions
Unfortunate the link given on this page for older firmware seems to be broken.