[plt-scheme] reference to undefined identifier

On Sun, Aug 9, 2009 at 7:03 AM, Erman Ersözlü<feberman08 at gmail.com> wrote:
> hi, i am new and i have a problem.i couldn't find any solution :( i am
> sure it is a basic and an easy problem..
> i saw these codes in a scheme book but they didn't work.it gives this
> problem: reference to undefined identifier: accumulate. i don't know
> what that means.what can i do to fix? i use pretty big language.

If I write a program like this:

> (define a 1)
> (define b 2)
> (+ a b c)

The interpreter will tell me:

reference to undefined identifier: c