I'm not clear whether you are trying to configure an iSCSI target or an iSCSI initiator. The instructions that you have been following are for an initiator. This is the client software that connects to another device that is sharing some of its resources via iSCSI.
If you have an iSCSI device then this may be what you want. But if you are trying to share some part of the disk space on your server as an iSCSI disk visible to another computer then you need to set up an iSCSI target on your server. Have a look at: http://www.heath-bar.com/blog/?p=203 .
I know it's not relevant to you, but if anyone is trying to set up a computer as a NAS server / iSCSI target by far the easiest way is to use FreeNAS. This makes the configuration of the components very simple.
You definitely want a target, and I appreciate that FreeNAS doesn't fit your needs. Have a go at setting up a target and post back if you still have problems; I've never done this on Ubuntu, but I've set up iSCSI targets on FreeBSD without any great problem, so it can't be too different. I can always have a play with a Ubuntu machine if necessary.
Whatever your final client (initiatior) you use, probably the easiest one to test on is the Windows iSCSI initiator if you have a Windows machine. It is particularly easy to access iSCSI disks from Windows (and next to impossible from OS X, without spending large sums of money, unfortunately.).