UJS for rails plugin Installation problems

Hello,

I downloaded and installed the latest UJS plugin.
I first got the error "uninitialized constant UJS" and this error wouldn't
go away no matter where I place the "UJS::routes" line in the routes.rb
file. The only way I found to get rid of this error is to run "rake
tmp:sessions:clear" but then I get another error which is "can't convert
Symbol into String" which refers to the symbol :unobtrusive that I added to
the javascript_tag as follows:
<%= javascript_include_tag 'protoype', :unobtrusive%>

Looks like rails can't load or find the UJS functions, because at some
point, and I don't know how, I got the error "apply_behaviour" not
defined...

Any ideas how to solve this problem and get UJS working?