Hello.. this is what I am doing now... Im trying to pupulate the combo box, but i'm gettin this error "Conversion from type 'DBNull' to type 'String' is not valid.". The funny thing is that I have a a text box that loads from the same BO and loads the same field, and it's working..

PS - I dont have any null info on the "nome_clube" field on the table.

Any Clues.. anyone?

Ricardo,

Your fill method is wrong on the cities.  Try this instead:

Public Sub FillCityByState(ByVal StatePrimaryKey As Integer)
        Me.FillDataTable("SELECT * FROM tb_cidade WHERE cidade_estado_id = " & StatePrimaryKey.ToString())

The code you had referenced its own property which was causing the error you described.  Try this and let me know how it goes.