Forum: Ruby on Rails Depot, private issue

I got the following error.
My guess is that there is a 'private' setting in the lineitem class, but
I can't find it :-(

"NoMethodError in Carts#show

Showing
/Users/kwadwoadu/src/ruby-test/depot/app/views/carts/show.html.erb where
line #11 raised:

private method `total_price' called for #<LineItem:0x007f98e108a0a8>
Extracted source (around line #11):

8:   <tr>
9:     <td><%= item.quantity %>&times;</td>
10:     <td><%= item.product.title %></td>
11:     <td class="item_price"><%= number_to_currency(item.total_price)
%></td>
12:   </tr>
13: <% end %>
14: <tr class="total_line">"