[TYPO3] templavoila error

[Daniel Jefferies]

I'm sure this has been answered before, however it looks like the 
archive search is down so here goes.

I've been trying to follow the Futuristic Template Building tutorial and 
  when I get to the point of calling TV from the template_page.html file 
I get an Internal Server Error in the far right pane.

I also notice the following error in the root pages header.
Data Structure ERROR: No source value in fieldname "tx_templavoila_ds"

My template TS was copied directly from the FTB tutorial.
page = PAGE
page.typeNum = 0
page.10 = USER
page.10.userFunc = tx_templavoila_pi1->main_page

Does "main_page" need to be replaced with something site specific?

What am I doing wrong?