Cannot create extended partition from gparted livecd

I am using gparted livecd to create the partitions I want for a dual boot. I have a modestly sized NTFS primay with Windows 7 installed, Now I need to create an extended partition from my logical partitions which will serve Ubuntu 13.04. Unfortunately, while in the new partition window, the option to select extended partition is grayed out.There is no swap partition mounted.How do I overcome this? What more need I tell you?Thanks.