how can i select the tab page

Hi friends,
Today i have a new problem.
i have a comboBox and a tabPageControl of the dev express.
 
i have deliveryMethod in my combo box.
and in tabPageControl there are tabPageCollection added in tabPageControl by me.
 
at 0 index there is paymentMethod
at 1st index there is delivery Method
at 2nd index there is NoteToBeneficiary
 
the default selected tab open is paymentMethod
 
Now my problem is that when ever my client select a value from the ComboBox
my tabPageControl must select the 1st index tabPage.
 
i apply this code

tabPageControl.ActiveTabPage.Index = 1

on the select index change of my comboBox.
 
but it is not working
when my tabPage open it not show any control which is present in my that tabPage.
 
Plz give me a right way to solve this problem...