Couldn't find Land without an ID

Rails
1

Hello everyone,
Mayby this is common issue but I can not fund solution:
In my I have this code

<% @all_lands.each do |land| %>

<%= land.name %> - <%= link_to 'Play', game_index_path(land) %>

<% end %>

and I can see list of Lands with link ‘Play’, but
when I click to link Play, I got error: Couldn’t find Land without an ID

In game/index cotroler I have this:

@l = Land.find(params[:id])

Basicly it is solution which is in every tutorial about rails, so I dont
know what is wrong.

Rails version is 3.0.7 and Ruby version is 1.9.2

Thanks for help