Do the fields fit within the first row of the portal in layout mode?
Are the fields' font colors set to the same as the portal's background color?
What relationship did you set up between the Tutorial: What are Table Occurrences? specified for your layout and the table occurrence specified for your portal?
Is "allow creation of records via this relationship" enabled for the portal's table occurrence?
Is there a related record in the portal's table where its match field's value matches the value of the corresponding match field in your layout's table?