1.put a dummy field on and have a rule set this field to the value of your usename, what is the output?
2. look at the column in the form library that it publishes to, what type is it set to.
You might have to publish a display name instead of a username and have the column that it publishes to set as a people/group type - email - can't remember off the top of my head, if you'll need a workflow to do this.