question regarding ISA server 2000

When I try to install ISA server 2000 on my server, with OS Windows 2000 Advanced Server, first need to run ISA server Enterprise initialization, after I confirm “ISA server Schema will be installed to the Active Directory”, it always prompts an error message “The format of the specified computer name is invalid”. Then it stopped.
What might be wrong? What shall I do to install ISA server then? Will this affect ISA running?