I created an apex class for sending outbound emails on a custom objec.t  The class is supposed to referenced a visualforce page rendered as pdf and attach it to the email.

I created the visualforce page and the pdf renders correctly when I view it in salesforce.com.  But when I send the email with the pdf attached, the pdf shows up as an attachment, but it is completely blank.

I think this has something to do with the apex class not passing the correct id to the VF page, but I'm not sure.  Any idea why this isn't working? 

public class EmailDraft
{

private Email_Draft__c ed;
public EmailDraft(ApexPages.StandardController controller)
{
this.ed=(Email_Draft__c)controller.getRecord();
}

public PageReference SendEmail()
{

// Reference the attachment page, pass in the account ID  
    
        PageReference pdf =  Page.VPL_Attach;
        pdf.getParameters().put('id',(String)ed.Value_Payload__r.id);
        pdf.setRedirect(true);

        // Take the PDF content 
   
        Blob b = pdf.getContent();

        // Create the email attachment 
   
        Messaging.EmailFileAttachment efa = new Messaging.EmailFileAttachment();
        efa.setFileName('attachment.pdf');
        efa.setBody(b);

Messaging.SingleEmailMessage mail = new Messaging.SingleEmailMessage();
String[] toAddresses = new String[] {ed.send_to_contact__r.email};
IF(ed.introduction_contact__r.email != null) {
toAddresses.add(ed.introduction_contact__r.email);
}
mail.setToAddresses(toAddresses);
if(ed.send_cc_contact__r.email != null){
String[] ccAddresses = new String[] {ed.send_cc_contact__r.email};
                  mail.setCcAddresses(CcAddresses);   
                  }
mail.setHTMLBody(ed.email_body__c);
mail.setSubject(ed.subject__c);
mail.setFileAttachments(new Messaging.EmailFileAttachment[] {efa});

Messaging.sendEmail(new Messaging.SingleEmailMessage[] { mail });

ed.approval_status__c = 'Approved & Sent';
update ed;

     PageReference next = new PageReference('/apex/email_draft_detail?id='+ed.id);
          next.setRedirect(true);
 
     return next;
 }    

}