I have exactly the same problem.
The most surprising thing is that I've been able to install it in graphical mode on a Linux Suse SLES 11.1 without problem.
On a AIX 18.104.22.168 server, without access to a graphical x-windows console, ie installing in text mode, I have the same failure.
I wonder if it is a problem of :
I finally succeeded the installation in graphical mode,
redirectiong the DISPLAY on the AIX server and using xming on my PC.
My conclusion is : bug affecting the text installer.