Problem in AutocompletecustomSource of textbox?

[vidhyaG]

Hi...

i am developing one windows application.in that i set autocomplete to textbox.

Eg: C1,C2,C3,C4,C5, C6,C7,C8,C9,C10 ,C11,C12

but while running autocomplete list displays not in the order.

like C1,C10,C11,C12, C2,C3,C4,C5,C6, C7,C8,C9

how to sort in correct order?

please if any one knows help me...