Are you saying that this line: $lm = `lm show_modeler -m wmers0c3.1`; is leaving $lm set to "" when you get to the print to file portion of your code? If that is the case is the lm utility you call actually printing to STDERR rather than STDOUT? If so, I'm pretty sure that the backticks won't grab STDERR. You might want to do something like this:

$lm = `lm show_modeler -m wmers0c3.1 >2&1`; #bash shell
[download]

I have no idea on other shells tho, That part of my brain melted 4 years ago.

Update: Ouch Fastolfe is correct. Turns out the bash part of my brain melted too. =P

--
$you = new YOU;
honk() if $you->love(perl)