How to open a modal dialog on another modal dialog?

Hi,

I am developing a plugin for Acrobat XI. The plugin adds a menu item. On clicking the menu item a dialog is opened.
The dialog have some text and two buttons. One of the button closes the dilaog and the other button opens another dialog. All the dialogs are modal.

I am using DialogBox  method to create both dialog boxes.

I am able to open the first dialog window using the above method (Please refer FirstModalDialog.jpg) but only the components of second dialog is displayed without any window (SecondModalDialog.jpg).

Can anyone tell me what am I doing wrong??

Thanks