starting Ubuntu on an SD card

[Lenny]

    Hi,
I used the Universal USB installer to put Ubuntu 11.4 onto an 8GB SD card 
with the intent of booting it on my netbook.
I know it works on this netbook, because I used to have it set up as a dual 
boot system.
Anyway, with an option of "run Ubuntu Live" that comes up, it only seems to 
boot to a flashing cursor, as my recruited eyes stated.
So, why is it difficult to boot this to the live option using the Universal 
installer?
Thanks for any help.
Glenn