Exec Xp_sendmail Error On SQL Server 2000

I have try to send a mail via xp_sendmail in Query Analyzer and it succeeded.
So I try to have it executed in a trigger but it failed.

Here is the trigger creation script and error message

use mlcb
go
if exists (select name
from sysobjects
where name = 'test' and
type = 'TR')
DROP TRIGGER TEST
GO

CREATE TRIGGER test on mlcb.dbo.trans_errlog
for insert
as
declare @email_subject varchar(100),
@email_content varchar(4000),
@email_recipients varchar(50)

set @email_subject='SQL Mail test mail'
set @email_recipients='some@world.com.tw'
set @email_content='this is a test mail, don't reply this mail'

exec master.dbo.xp_sendmail @recipients=@email_recipients,@subject=@email_subj ect,@message=@email_content
GO

Error Message:
Server: Msg 2812, Level 16, State 62, Line 6
Could not find stored procedure 'master.xp_startmail'.
The statement has been terminated.

Appreciate any prompt reply.

JD