sybase Database Backup

Dear Expert,

I am using Sybase Database 15.0 with unix, as i new to Sybase please me  how to take backup of Sybase Database.

i get the below error

1> dump database pubs2 to 'd:\dump'

2> go

Msg 7205, Level 17, State 2:

Server 'BHAVANIPC', Line 1:

Can't open a connection to site 'SYB_BACKUP'. See the error log file in the ASE

boot directory.

Msg 7205, Level 18, State 3:

Server 'BHAVANIPC', Line 1:

Can't open a connection to site 'SYB_BACKUP'. See the error log file in the ASE

boot directory.

Also we opened the backup server

Thanks & Regards,

Akhila