This post reminded me of this little sitcom:
Greg: [thinking] Let's see what the tech support E-Mails have to say today.
E-Mail: Hello. I just set up my new PC and it doesn't work correctly. Do you have any ideas? Signed, A Paying Customer.
Greg: [ rappy tap tap jab] Yep, I sure do. Signed, Tech Support.

I am guessing, you are installing JSMF on Joomla 1.5.x? That won't work. Nor will it in the future.