question about DrScheme

[Cynthia <tjioe@elang.stts.ac.id>]

Hi, please introduce. My name is Cynthia.
I am just a beginner to use DrScheme 101. Only a few days ago. I was trying
to run some files at htdp like hangman & pingp-play. But I can't do it.
There was an error message :
C:\PROGRAM FILES\PLT\collects\htdp\big-draw.ss: 7.20-7.34: Unbound
signature name: plt:userspace^

My questions are :
1. What's wrong ? What can I do to make it work ?
2. Can you tell me some collections of interesting artificaial intelligence
programs that I can run in DrScheme ?
3. Do the language of DrScheme using the standard of Scheme language ?

I am expected for your answer. This language is really good & I like the
playing cards games. I want to learn about it. Thanks for your attention.
I'll be waiting for your reply.

Regards,
Cynthia