Class Methods find_for

I am having a problem with my find_for method in my BankAccount class. IRB is giving me this error:

2.0.0-p247 :006 > bank_account = BankAccount.find_for("Melissa", "McGinnis")

NameError: undefined local variable or method last_name' for #<BankAccount:0x007fe02c2ee028> from /Users/brittmcginnis/[projects]/deepdive/bank_account.rb:19:infull_name' from /Users/brittmcginnis/[projects]/deepdive/bank_account.rb:9:in block in find_for' from /Users/brittmcginnis/[projects]/deepdive/bank_account.rb:9:ineach' from /Users/brittmcginnis/[projects]/deepdive/bank_account.rb:9:in find' from /Users/brittmcginnis/[projects]/deepdive/bank_account.rb:9:infind_for' from (irb):6 from /Users/brittmcginnis/.rvm/rubies/ruby-2.0.0-p247/bin/irb:13:in `<main>'

Here is my program: class BankAccount

def self.create_for(first_name, last_name)
    @accounts ||= []
    @accounts << BankAccount.new(first_name, last_name)
end

def self.find_for(first_name, last_name)
    @accounts.find {|account| account.full_name == "#{first_name} #{last_name}"}
end

def initialize(first_name, last_name)
    @balance = 0
    @first_name = first_name
    @last_name = last_name
end

def full_name
    "#{@first_name} #{last_name}"
end

def deposit(amount)
    @balance += amount
end

def withdraw(amount)
    @balance -= amount
end

end

bank_account = BankAccount.new("Brittan", "McGinnis") puts bank_account.inspect