Invalid command: Processes: FindProcess

Hi!
I'm executing a NSI script in my XP MS-DOS command window, and I get the above error. Any ideas what I might be doing wrong? I'm a noobie at this, working on someone else's project, so I may be overlooking something really obvious here. Any ideas?

Thanks!

Best,

Steve

You are missing the processes plug-in.

try Processes::FindProcess