how to add combobox in Reporting services tools

i have to display a combo box and i should display list of cities in that combobox in the MSSQL reporting services.But if i check report designer,combabox is not available.how to add combobox???pls help me.it is very urgent.


Thanks,
Kannan

Thank u dineshasankha for ur reply for my Query.But in that article i didnt find out how to add combo box in reports.
Any other solution if u have.pls let me know.

thanks,
regards,
thirukannan2003