Adding column to existing table in build 672

I may be completely overlooking the obvious but I am trying to add a new field in the column to an existing table within the edit SQL query page. When I select a blank field I can type in the name I want or select from a drop down of existing fields. After I enter a name the table name field remains blank without adopting the name of the table I am editing. When trying to advance to the next page after editing I get a error message which says "Cannot retrieve columns information. Please modify SQL query and try again. Error message: Unknown column '' in ''
Thanks,
Noal