So you committed a Scheme error. Side remark: a Scheme error
always seems to result in a log file ending in a wistful
Parsing...
with no further information, like a message scratched on a wall by the
last human at the world's end.
But at least you can be pretty sure that a Scheme error is the problem,
so you can use a fine-tooth comb on your Scheme expressions looking for
the error. I've taken to keeping a separate file with a handwritten list
of all the Scheme expressions that *do* work, as a help in finding my
coding faults.