[Catalyst] Trouble using Catalyst::Controller::FormBuilder

[Eric Berg]

I'm trying to get Catalyst::Controller::FormBuilder to work, but am 
running into some problems.  Per the docs, the config should be like this:

use base 'Catalyst::Controller::FormBuilder';

But my class is from a brand-new Catalyst install, so it's using extends like this:

BEGIN {extends 'Catalyst::Controller'; }


So I changed it to this:

BEGIN {extends 'Catalyst::Controller::FormBuilder'; }

And now I'm seeing this error:

Couldn't load class (GLR) because: Couldn't instantiate component 
"GLR::Controller::Payment", "The 'add_attribute' method cannot be called 
on an immutable instance at 
/usr/local/lib/perl/5.10.1/Class/MOP/Class/Immutable/Trait.pm line 32


Can anyone steer me in the right direction to get this working?  BTW, 
I'm a long-time Perl guy, but this is my first Catalyst app.

Thanks!

Eric