[plt-scheme] problem running moby scheme compiler from command line

i first installed required plt-scheme>=4.2 and then downloaded the
moby source from git.
created a directory called work and placed the moby source into the
work directory.
cd work
then added a PLaneT local link to the moby directory:

$ planet link dyoo moby.plt 2 <<some-high-number>> moby.

i replaced the some-high-number with 5.

then tried to execute moby from command line as follows:

$ cd moby/examples

$ mred ../src/moby.ss falling-ball.ss

to which the output was

/home/deepak/work/moby/src/moby.ss:77:44: compile: unbound identifier
in module in: Loc->string

 === context ===
standard-module-name-resolver



can u plz help me wid this problem