BackOffice Small Business Server

Installing Microsoft Back Office Small Business Server 4.0 uprgading to 4.5, no other operating system is an option here.
Trying to install SBS with 32-bit Wide SCSI controllers. Using the 3 startup disks pressing F6 to select the type of SCSI device that all works OK. At the end of the startup disks the error I am recieving is

Setup was unable to locate a CDROM drive. Make sure your CD ROM drive is switched on and properly connected to your computer. If it is a SCSI CD ROM drive, makesure your SCSI devices are properly terminated. F3 to exit.
Also tried with the option using Compaq Drive Array. The CD ROM does work as I have run a CD in the drive with no problems. All I want to do is get this installed.