[plt-scheme] opengl on windows

Hello,

I have a problem with plt-scheme under windows. I would like to
use OpenGl and I managed to use Scott Owens' OpenGL bindings
under Linux. However under Windows I get the following error
message:

setup-plt: Compiling .zos for sgl at C:\PROGRA~1\PLT\collects\sgl
setup-plt: error loading installer: string-append: expects type <string> as 1st
argument, given: #f; other arguments were: "/collects/compiler"
setup-plt: Done setting up
setup-plt: 
setup-plt: Error during General Install for sgl (C:\PROGRA~1\PLT\collects\sgl)
setup-plt:   setup-plt: error loading installer: string-append: expects type
<string> as 1st argument, given: #f; other arguments were: "/collects/compiler"

I have MS Visual Studio 6.0 installed on the system. I guess
there is nothing set as a compiler. (I do not know whether it
matters, but first plt-scheme was installed then MS Visual Studio.)
I am new to plt-scheme (not to scheme), so I do not know what to set 
and how. Anybody can help me with this ?

Thanx, in advance.

                                Peter Ivanyi