[Orgmode] Org-beamer problems

[Bill Moran]

I have installed the latest (git) version of org-mode and have stripped out all
customizations from  I think. I've copied Eric's two column example from here

http://orgmode.org/worg/org-tutorials/org-beamer/tutorial.html

with the headers given there. And I can't get either blocks or columns to work.
There is no block or column command in the latex produced from the org file. 

I guess it's something to do with the value of the variable 

org-export-latex-classes 

but have been unable to find a statement of what that should be. I think I've
undone all customizations of that  variable from earlier attempts but can't be
sure. 

Thanks for your help.

Bill