Adding columns to table

Hi,

I have a added a table with 6 columns in a adobe form (transaction SFP - layout ) and have done all the data binding, formatting. Now i need to add a new column to this table. But i am not able to add a new column, the table properites ( rows, columns ) in object palette is also disabled. Table has a header row and body row with 6 cells for each field.

How can i add a new column now without disturbing the existing columns ?

Thanks

Subhashini