Partition used space isn't recognized

Hi, I bought a Notebook Toshiba L845 with W8, and I want to Install W8.1 and Kali Linux.
I formatted mi hdd and installed W8.1. (I forgot to leave free space for the kali partition -.-)
So then I booted from Kali and i wanted to resize partition NTFS with gparted, but the disk appears with no partition, like if all of the space was free.
The message that gparted sends was: Warning: /dev/sda contains GPT signatures, indicating that it has a GPT table...(Continues)

Also, when I run Kali Linux instalation, all te space is recognized as free.

What can I do?

PD: Sorry for my basic english, and for my little knowledge about the illimited and amazing world of informatic. Thanks you.