[CentOS] Kickstart issue: 'dialog' doesn't work in %post, CentOS 5.5

On Jun 9, 2010, at 5:39 PM, John Doe wrote:

> From: Zhang Huangbin <zhbmaillistonly at gmail.com>
>> I'm trying to customize a CentOS installation cd, but got 
>> trouble with kickstart.
>> I want to use dialog[1] for command line based 
>> user interface, but it can't display correctly in kickstart with CentOS 5.5. 
>> Same ks file works with CentOS 5.3 (both i386 and x86_64).
> 
> What does "can't display correctly" mean?
> Checked /etc/termcap for available terminals?

I use 'chvt 3' in ks file to switch to 3rd tty, but it stays in 1th tty (installation console).
Swith to 2nd tty with 'Ctrl+Alt+F2', run 'ps' command, i can see dialog process is running.