Booting from a Logical Partiton

#1
Hi,
I'm running EasyBCD on my notebook computer using Window 7 (2 internal disks)
I am using an external USB hard drive to install Ubuntu.
Since I want to install a number of different versions, I've partitioned my USB disk as follows:

1 primary - swap
2 primary - home
3 extended
4 logical - OS1 <= Ubuntu 13.04 installed here
5 logical - OS2 (empty)
6 logical - OS3 (empty)

EasyBCD is not able to boot my Ubuntu and drops me to the 'grub4Dos' command line.

In grub4Dos 0.4.5c

find reports:
(hd0,0)
(hd1,0)
(hd2,0)
(hd2,1)
[which are C: D: swap & /home]

Where are my logical drives?

Can someone please advise how I can get grub4Dos to see my logical paritions. URL to a 'to the point' setup guide would be nice.

Cheers,
Nap

---------- Post added at 11:29 PM ---------- Previous post was at 02:11 PM ----------

I have now changed my partitions, and reinstalled Ubuntu as follows:

1 primary - swap
2 primary - home
3 primary - /boot
3 extended
4 logical - OS1 / <= (root)
5 logical - OS2 (empty)
6 logical - OS3 (empty)

I put /boot on a primary partition since Grub4Dos was unable to find my logical partition /. I figure that once it loads the 2nd stage, the rest will follow.

However it still drops to the Grub command line prompt when I select the Ubuntu option from the menu.
(I tried using the advanced option to change the drive to BOOT as well, but same thing happening.)

When I used root=(hd2,1), it reported that my filesystem was ext2fs (which is wrong, it is ext4).
When I tried to set root to the boot partition (hd2,2), it gave me an error.

Help on this topic is really hard to find as the search engines confuse Grub4Dos with GNU Grub, and those I've managed to find are often derailed or concern situations totally different to mine.

I don't know what to do at this point. I do not want to install the OS in to a primary partition AT ALL if I can avoid it.

Cheers,
Nap