rake task: uninitialized constant

I have this rake taks:

CUSTOM_MONTHS = [nil, "GEN", "FEB", "MAR", "APR", "MAG", "GIU", "LUG", "AGO", "SET", "OTT", "NOV", "DIC"]

def parse_date_string(date_string) begin    day, month, year = date_string.split("-")    Time.mktime(year, CUSTOM_MONTHS.index(month), day).strftime("%Y-%m-%d") rescue    return nil end end

namespace :import do desc 'import pericolanti' task :pericolanti => :environment do    UnsafeBuilding.delete_all    puts "Creating unsafe_buildings..."    lines = FasterCSV.read('/home/user/Docs/pericolanti')    lines.each do |row|      if row.any?        # controllo che row[10] e row[11] non siano stringhe        barrier_meters = row[10] if row[10].is_a?(Float) or row[10].is_a?(Integer)        square_meters_public_land = row[11] if row[11].is_a?(Float) or row[11].is_a?(Integer)

       practice_number = row[17].to_i        practice_date = parse_date_string(row[3])        practice_new_date = parse_date_string(row[3])        inspection_date = parse_date_string(row[7])        intervention_date = parse_date_string(row[9])        remove_date = parse_date_string(row[13])        notification_date = parse_date_string(row[14])        expiry_date = parse_date_string(row[15])        cordoned_off = true if row[8] == "Si" or row[8] == "SI"        cordoned_off = false if row[8] == "No" or row[8] == "NO"        UnsafeBuilding.create!({ :practice_number => practice_number, :address => row[6]

etc. etc.

rake import:pericolanti works well but if I do rake import:pericolanti RAILS_ENV="production" it says: uninitialized constant UnsafeBuilding. Why?

Solved: I need require "/app/models/MyModel" in the rake file.