MS SQL 2008 error when trying to execute script.

I trying to automize a SQL Backup by executing a SQL script from my pc at work but i get an error:

The batch script to start the sql script:

echo off
sqlcmd -E -S SERVERDB\MSSQLSERVER -i C:\Users\MYNAME\Desktop\TestBackupSql.sql
SET /p delExit=Press the ENTER key to exit...:

/* HResult 0x57, Level 16, State 1
SQL Server Network Interfaces: Connection string is not valid [87].
Sqlcmd: Error: Microsoft SQL Server Native Client 10.0 : A network-related or in
stance-specific error has occurred while establishing a connection to SQL Server
. Server is not found or not accessible. Check if instance name is correct and i
f SQL Server is configured to allow remote connections. For more information see
 SQL Server Books Online..
Sqlcmd: Error: Microsoft SQL Server Native Client 10.0 : Login timeout expired.
Press the ENTER key to exit...: */

I can open a sql session to serverdb from an instance on my pc.I guess this means there might be someting wrong with my syntax or something i've omitted from script file?