Help! with WD4001FAEX

Hi guys,i recently buy my 4 TB WD Black WD4001FAEX and i have a problem with windows 7 64 Bits a install and only recognize me 2 TB i try to create the 1.6 TB remaining a new partition and won’t let me, is there any manual or instructive so i can add remaining space? plz help!!!

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I read abot 2.1TByte limit mbr

Try to divide it by another app and restart  maybe resolved

Fixed, i used Disk Unlocker (free software that cames with the DVD of my ASUS Motherboard).