CSV Generator errors

I'm trying to use CSV Generator. Following instructions in the help file, I've created a CSV file and browsed to it from the selector. Then I click the Generate button and I get an error:

"Invalid Format: Provide sAMAccountName as header"

Trying to follow those instructions, I opened the CSV file, put in the value "sAMAccountName" in the first row, and tried to Generate again. I get a different error:

"There is no such object"

Any hints on what's going wrong, or how I get this to work?

Also, going into the Advanced button and picking advanced attributes doesn't seem to do anything - none of the columns changes once I exit, and it's empty when I go back to that window.

Thanks.