Combobox Datasource

Hi,

I have added a comboBox column in my datagrid and there is another
datagrid..when user changes the selection in the second datagrid i need to
set a different datasource to the comboBox. The problem is when i try setting
the datasource second time...even if i have values in the table which i set
as datasource , the combobox's datasource still shows it as undefined value.

please help!!

-Kina