rn102 nas

Hi guys and girls i have a rn102 nas which im tyring to put in 2 x western digittal wd4003fpbx 4tb hard drives but it will not recognize these. It worked fine with my 1 tb seagates but i needed heaps more room .. also the winrar ap does not let me install the lastest update saying the file is corrupt .. somebody help me or its a new nas time. Thanks