[plt-scheme] Turtles module gives an error with 4.2

If I write the following two lines in DrScheme 4.2 and press Run, it
gives me an error message.

#lang scheme
(require graphics/turtles)

The results is the following message.

>define-compound-unit/infer: untagged initialization dependent signature mred^ is
>supplied from a later unit with link temp3

Another attempt. This program works and shows the "spyro-gyra" image.
I suppose the problem is with the traditional turtles module, since
the two lines are all it takes for the error to come up.

#lang scheme
(require graphics/value-turtles)
(require graphics/value-turtles-examples)
(spyro-gyra (turtles 200 200))

This happens to me both with 4.2 that I installed on Windows with the
installer and another 4.2 that I built from the source distrib on my
laptop with Ubuntu 8.10.

Finally, I spotted a typographical error: The documentation has a
wrong name for the value-turtles-examples module on the Value Turtles
page (doc/turtles/Value_Turtles.html). It doesn't have the s at the
end of turtles under the heading "2.1 Examples," saying "(require
graphics/value-turtle-examples)". The text below is missing the same s
from the name too.

Pekka Karjalainen