How work NSHelpPanel?

[German Arias]

Hi, I want make a help panel to my app, but I don't know how work
this. In Mac dev center there isn't information about this class. In
docs.sun.com there is information, but don't work. I do this: I create
a new folder with the name English.lproj and, inside, another folder
with the name Help. Then I create two files (in Help folder) with the
names TableOfContents.rtf and Index.rtfd. Add a new method call
showHelpPanel in AppController.m and connect this with the Help option
in the menu. This method send the message

[NSHelpPanel sharedHelpPanel] ,

don't work. Then, I delete the folder English.lproj, and add a simple
file with the name help.rft. Now, in Project Center, in Project
Inspector a add this file in the field Help file. But, when I run my
app, I get the error

2008-12-26 18:12:19.372 Test2[5361] File NSView.m: 523. In [NSTextView
-initWithFrame:] given negative width

any suggestion?