Don't use the built in app. Format it under Windows or boot Parted Magic. I don't think that anyone here can debug Lacie software.
You might look at the partition info under Drive Management and see if you actually have a small partition or you have a messed-up large partition. You may also have to increase the default cluster size to use the whole drive. Per Wikipedia, "...limiting the FAT32 volume size to 2 TB for a sector size of 512 bytes and 16 TB for a sector size of 4,096 bytes."