chimera@HOMEPC:~$ sh PlaneShift_CBV0.3.011.linux.x86-2.run
Creating directory ps.cb.03.011.linux.x86-2
Verifying archive integrity... All good.
Uncompressing Planeshift Crystal Blue Version 3.011 relase 2..
Checking if dialog program is installed...
Dialog program, which is required to use this software, cannot be found.
Please install this program before continuing Planeshift installation.
You may obtain it from your distribution FTP or install disk.


what should I do?

System specs: Ubuntu 5.10, gnome 2.12