Importing Student Names from Numbers into idoceo

I have imported a Numbers file with my student names into idoceo. It appears in the "Resources" section. However, I can't get it add the names to the corresponding class. I tried "copy to" and "add to" and all of the other possibilities I saw in the help files. But, when I go to that class, it's still blank.

Hi,
The current iOS7 version of Numbers will export to XLSX file (which is not supported in iDoceo yet) instead of the XLS file of previous versions.
You should export from Numbers as CSV file instead