problem with the nav virual appliance

hello I tried to use the nav ( lenny ) virual appliance with virtualbox ( by importing the ovf ) but it failed. vitrualbox complained that the vmdk was incorrect. i downloaded it again on another computer and tried to convert the vmdk with qemu-image but it also complained that the vmdk was incorrect. could you confirm that the latest vmdk uploaded on your server really works ? ps: the etch vmdk works fine thanks mke