Pipe with `tee` in a `for` loop

This is probably a newbie's escaping problem. I'm trying run command in a for loop like this

$ for SET in `ls ../../mybook/WS/wsc_production/`; do ~/sandbox/scripts/ftype-switch/typesort.pl /media/mybook/WS/wsc_production/$SET ./wsc_sorter/$SET | tee -a sorter.log; done;

but I end up with sorter.log being empty. (I'm sure there is some output.) If I escape the pipe symbol (\|), I end up with no sorter.log at all.

What am I doing wrong?

$ bash --version
GNU bash, version 4.1.5(1)-release (i486-pc-linux-gnu)

Edit: Oops, /media/mybook/ fell asleep, so there actually was no output. The code was correct in the first place. Thanks to all for comments, though.

Solution

My deepest apologies, the problem was somewhere else and my script actually did not output anything at all. Now it works.

Two reasons why I got the illusion that the problem is in escaping:

of course, lack of confidence in bash scripting, which is effect of lack of knowledge and experience
and also, lack of attention--it did not come into my mind that the disk on USB fell asleep, so when I tried the loop there actually was no output

Well, that's for some stumbling on my way to knowledge... :)