[plt-scheme] Cannot start drscheme

I build and installed Mandriva's drscheme RPM, but when I run drscheme, 
actually mred is started with the message that I should start drscheme to 
get a better window.

It seems drscheme is a schell script which launches
"${bindir}/mred"  ${xa+"-display"} ${xa+"$xa"} ${xb+"-geometry"} ${xb
+"$xb"} ${xc+"-bg"} ${xc+"$xc"} ${xd+"-fg"} ${xd+"$xd"} ${xe+"-font"} ${xe
+"$xe"} ${xf+"-name"} ${xf+"$xf"} ${xg+"-selectionTimeout"} ${xg+"$xg"} 
${xh+"-title"} ${xh+"$xh"} ${xi+"-xnllanguage"} ${xi+"$xi"} ${xj+"-xrm"} 
${xj+"$xj"} ${xk+"-iconic"} ${xl+"-rv"} ${xm+"+rv"} ${xn+"-synchronous"} 
${xo+"-singleInstance"} -N "$0" '-ZmvqL-' 'drscheme.ss' 'drscheme'  ${1
+"$@"}

drscheme.ss is installed in /usr/lib/plt/collects/drscheme/drscheme.ss

The whole contents of the RPM can be seen here:
http://sophie.zarb.org/viewrpm/f9cb441a970753b1034af8864e0e5719

What could be the reason that drscheme does not start up, but only mred?

-- 
Frederik