A few potential problems (Net::SNMP may take care of some of these for you):

push(@request, ("1.3.6.1.4.1.2011.6.10.1.2.4.1.2.$rand_value",INTEGER,
+6));
                 # ^ -- Add a leading dot here
[download]

You are missing the leading dot on your fully-qualified OID; the examples in Net::SNMP don't include it either, though, but it may be worth a try.

You might also need a trailing .0 after $rand_value to specify the (scalar) index, unless you've accounted for that in $rand_value.

An ErrorStatus of 7 normally corresponds to a WRONGTYPE error. My SNMP is a bit rusty, but I note you are setting up an INTEGER varbind but passing in '6'. Do you need to pack that to a 32-bit signed int? Try:

Finally, what does $session->error report? Is it the same as what you see in the log? What happens if you send separate set_request()s for each varbind—i.e., do all of them fail similarly, or is it a more specific problem?

Sorry for the "multiple guess" answer, but it's been a while, and I have no environment capable of testing this. Hope it helps!