Fedex plugin Rails Issue

I working on an existing code base for a client. The app is built in
rails
2.3 and uses the fedex plugin. Now i have develop a functionality for
shipping the goods using international priority service type, the
problem
i’m facing is when ever i make a call to the fedex api for a shipping
label
it returns an error

“Fedex::FedexError: Unable to get label from Fedex: Customs Value is
required”

Can some one help me how to mention the customs value for the label.

This is how my code is:

price, labels, tracking_number = fedex.label(

    :shipper => { :contact => shipper, :address => origin },
:recipient => { :contact => recipient, :address => 

destination.merge(:residential => false) },
:service_type => service_type,
:packages => [{:length => 3,
:height => 4,
:width => 5,
:weight => 5,
}],
:weight => 5,
:commodities => commodities,
:customs_value =>{:currency => “USD”, :amount => “100” },
:residential => is_residential_destination)

Thanks In Advance.