Problem with Required Attribute

I added a custom field: a check box with this value in label: I have read and accept the Rules and Regulations
It is set as a required attribute.
Abbreviation is set at “rules”

However, even though the box is checked during the checkout process I get this message :
I HAVE READ AND ACCEPT THE RULES AND REGULATIONS IS A REQUIRED FIELD.

http://wordpress.org/plugins/woocommerce-checkout-manager/