Proliant ml-330, adaptec raid-5, 4-disks array probem

[harish_6]

Server is proliant ML330 with adaptec raid-5 and 4 scsi devices are installed. Server was functioning fine, then a problem came showing the status of one scsi drive as FAILED. so replaced the scsi with new one and rebuilded, then worked fine.
Once again there was a problem in another scsi disk device, so i have removed it and the server was not booting. After removing the failed disk, i installed WINDOWS NT4.0 on the raid-5 with 3 scsi disk optimal functioning and made it function so that there should not b any time gap of stopping server.
Now I got a new scsi disk for that replacement, i fixed this one to the emptied position, then started the server, it shows out of four, only two are optimal fucntioning and the other two are missing.i.e. the previous out of 3 scsi, even one is not showing now. this is the problem, plesse solve this what shall i do, shal i reinstall with smart start server.
i have tried to create a new array but it shows the error cannot create due to either raid non-availability or no space in disk array.
can anybody please solve this urgently and reply..
Thank You in advance.