VB textbox can not show some Cyrillic letters.

Hi All,

I have one problem related Unicode.
In the VB text box, I can not write come Cyrillic “ө”, ”Ө”, ”ү”, ”Ү” letters.
If I write those letters VB text box shows “?” letters instead of them.

But those letters have being written in Notepad and Word and some system dialogs. (For example, Run dialog)

Why VB text box can not write those letters?
How I write?

Note: Cyrillic ‘ө’ letter locates on letter ‘f’ position.

Please see attached screen dumps for more information.

use a rich text box with a cyrillic font that allows