Sometimes current information does not appear in a Sharepoint Designer 2007 workflow email

I have a SharePoint 2007 form library which uses an Infopath 2007 form. Once a form is submitted and email is sent to an approver which includes key pieces of information from the current form. (Request Group, Request Type, Start Date, Requested By). Sometimes it works perfectly and then sometimes the email is blank. These pieces of information are also fields in the form library and always show up, even if it doesn't appear in the email.

Is there something I should be checking?