Check all checkboxes

[Colhawk]

Hi all,

I am having a major brain melt down. I have a timesheet which works out how much bonus a list of employee's get depending on the recycling rate of the site the month before.

I have added in a check box for each employee which the manager can check when the employee is entitled to receive the bonus and it will then work out how much they should receive.

I am trying to add another checkbox to say to check all the other boxes on the sheet but for some reason I just cannot make it do it.

I have attached a copy of the sheet I am using.

Thanks for anyones help!