I have a Overland NEO backup system using VTL with migration to tape. The VTL(REO Box) runs fine but the tape unit keeps giving me errors. The migration to tape occurs after the data is written to the VTL. The Physical library has 3 tape drives which are HP Ultrium LTO4. The OS is Windows Server 2003, SP2. I am using Arcserv R15. Every time I try to erase or format it gives me a "ILLEGAL COMMAND" error. It also marks the tape as Unreadable. I have replaced the some tapes with new tapes with the same result. I am using HP drivers currently. CA and Overland have not been much help. Any help would be GREATLY appreciated.