Still can't for "agree to terms" with email submit button...

I hope someone can help. I've been all through the forum and around google too.

I have a nice script which I modified from the AcrobatUsers group. But, I need the reader click on a checkbox before they can email the form. Here's my code for the "mouse-up" action of the email submit button, anyone have any ideas?

//
// Before sending the data, make sure that all required
// fields are valid
//
// The "Ex1ValidFields" fucntion is located in the document script
// If you copy this button action then you will also need to delete
// this first if statement or copy the "Ex1ValidFields()"
// function and modify it to work with your form.
//
// This is the form return email, It’s hardcoded
// so that the form is always returned to the same address
// Change address on your form
var cToAddr = "name [at] email [dot] com";

// Get the client CC email address
var cCCAddr = this.getField("SalesRepTarget").value;

// Now get the beneficiary email only if it is filled out
var cBenAddr = this.getField("Benemail").value;
if(cBenAddr != "")
cCCAddr += ";" + cBenAddr;

// Set the subject and body text for the e-mail message
var cSubLine = "Advertising Form Returned from "
+ this.getField("Advertiser").value + " "
+ "c/o " + this.getField("Agency").value;

// Set the body text for the email message
var cBody = "Thank you for submitting your form.\n" +
"Save the mail attachment for your own records";

// Send the form data as an FDF attachment on an email
this.mailForm({bUI:true, cTo: cToAddr, cCc: cCCAddr,
cSubject: cSubLine, cMsg: cBody});