[Devmon] "Can't locate Math/BigInt/Calc.pm in @INC" error

[<Lor...@pf...>]

Guys, 

I'm just trying to install devmon on my BB 1.9c server running on RH Linux 
7.3 (oooooold, I know).
Now, I installed SNMP_Session 1.08 ok, set up devmon to run under the bb 
user via cron.
Nothing happened.

Running it by hand, here is the error I'm getting:

$ ./devmon -vv -f --readbbhosts
Can't locate Math/BigInt/Calc.pm in @INC (@INC contains: 
/usr/local/devmon/modules /usr/lib/perl5/5.6.1/i386-linux 
/usr/lib/perl5/5.6.1 /usr/lib/perl5/site_perl/5.6.1/i386-linux 
/usr/lib/perl5/site_perl/5.6.1 /usr/lib/perl5/site_perl/5.6.0 
/usr/lib/perl5/site_perl /usr/lib/perl5/vendor_perl/5.6.1/i386-linux 
/usr/lib/perl5/vendor_perl/5.6.1 /usr/lib/perl5/vendor_perl .) at 
/usr/local/devmon/modules/dm_tests.pm line 20.
BEGIN failed--compilation aborted at /usr/local/devmon/modules/dm_tests.pm 
line 20.
Compilation failed in require at /usr/local/devmon/modules/dm_config.pm 
line 24.
Compilation failed in require at ./devmon line 19.
BEGIN failed--compilation aborted at ./devmon line 19.
$

$ find / -name Calc.pm 2>/dev/null
/usr/lib/perl5/vendor_perl/5.6.1/i386-linux/Date/Calc.pm
$

Am I right in assuming that THIS Calc.pm is not the right one?
If so, how do I go about fixing this issue?

Thanks in advance

Loris