undefined local variable or method `calendar_date_select_includes' for #<ActionView::Base:0x7bfd920>

Here's what I did:

1. gem install calendar_date_select

2. Then in my environment.rb I put:
config.gem "calendar_date_select"

3. And in my template file:
<%= javascript_include_tag "prototype" %>
<%= calendar_date_select_includes %>

But still an error posts like this : undefined local variable or
method `calendar_date_select_includes' for #<ActionView::Base:
0x7bfd920>

My ruby is 1.9.2 rails 2.3.5 gems 1.5.2

Here's what I did:

1. gem install calendar_date_select

2. Then in my environment.rb I put:
config.gem "calendar_date_select"

3. And in my template file:
<%= javascript_include_tag "prototype" %>
<%= calendar_date_select_includes %>

Did you restart the app after changing environment.rb?

Fred