I was testing report by mail and I tried to submit the form using default values.
Validation set me an error message: 'description' was required, so I filled it (easy to understand).
Then validation asked me for 'reports' required field. Well, any of the fields is called 'reports'. It's meaning "Statistics included" is required, so you can't build a mail report with all the data for the chosen website but you must check any of them.

• The form is missing a "select all statistics" checkbox
• "all websites" value should be apart, because it will include that choosen statistics, for whole all the websites
• In each way, the field(s) causing error should be clearly distinguished