Assignement settings: how to display Annotate pdf column

Hi,

I have set up two assignments, one which requires a pdf submission and another which requires no submission.

For the first assignment, the one which required a pdf submission, I wanted to download the annotated pdf, but found no way to do this.

Then, as I was viewing the second assignment, I noticed a column in the table of assignments called 'Annotate pdf' (even though this assignment required no submission and, so, no annotated pdf).

The feedback settings are the same for both assignments and yet I cannot make the 'Annotate pdf' column appear in the first assignment.

This is in Moodle 2.9.

Could anyone suggest where I've gone wrong?

Thank you for your help,

Susanna