Error with Email Dialog and array of addresses

According to the docs, the email dialog should be able to take an array of contacts and send it out as an email, instead of having to do one at a time. When I try that, I get an unrecognized selector error.

var a = new Array();
for(i=0;i<response.length;i++){
a.push(response[i].email); // looping through and adding the emails
}
 
var emailDialog = Ti.UI.createEmailDialog();
            emailDialog.subject = "Hello from Titanium";
            emailDialog.messageBody=Ti.App.Properties.getString('first_name')+' ' + Ti.App.Properties.getString('last_name')+ ' would like to connect with you on the Sports #1 Social Network'; //Set email Message
            emailDialog.toRecipients = a;
            emailDialog.open();

Any ideas as to what I'm doing wrong? I can do a console.info on the "a" array and its full of addresses. I also tried just making a string of CSV addresses, and it fails.