Net Use Error 1326 Windows Server 2003

I developed a DOS batch file on my Windows Vista laptop that connects to a server via VPN, and once connected does a 'net use' to map a drive for my batch file to use on the computer I'm connected to.

The batch file executes on my Vista laptop, but when I copied it over to the Windows 2003 Server, the net use command gives me a 'System Error 1326 Logon failure: unknown user name or bad password'.  Is this a permissions issue on the server or is there some settings that I need to take into consideration?  

Here is how my command looks:
net use z: \\10.0.x.x\thisdata /user:user1 pass1

I've tried several variations of the command, without password, without username and password, from the command line, all of which required me to enter the username and/or password, but they all fail with the same error message 1326.
Any assistance is very much appreciated.