[CentOS] USB thermometer - perl script - problem

Hopefully someone here could help. I need to debug, but I don't know 
much about perl.

I bought a cheap USB thermometer:

http://www.amazon.com/dp/B002VA813U?tag=grepular02-20

And found directions for use (for Linux) here:

https://grepular.com/Using_Linux_to_Monitor_Room_Temperature_Remotely_and_Cheaply

On a CentOS 6 machine, I have connected the USB device (it shows here as 
"Microdia":

[root at farm2 scripts]# lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
Bus 001 Device 003: ID 0424:2514 Standard Microsystems Corp. USB 2.0 Hub
Bus 001 Device 006: ID 0c45:7401 Microdia

With CPAN, I installed the  Perl module 
Device::USB::PCSensor::HidTEMPer, as directed. That seemed to be 
successful.

Now my perl script (as copied from grepular.com, see above) gives no 
error messages about missing modules. But I should get a temperature 
reading as output. Instead, I get no output at all.

When I add to the script this:
	print $pcsensor;
I get this as output:
	Device::USB::PCSensor::HidTEMPer=HASH(0x14d8900)
But this:
	$pcsensor->list_devices();
gives no output.

How could I debug this?

- Jussi