MPLS dynamic model instrumentation interface: SNMP-E-EINVALID

Hi,

I'm trying to monitor a mib-oid. For that I've created the following interface that I'm using as an instrumentation class:

interface TestInstrumentation : ICIM_Instrumentation {

    instrument SNMP {

         sysDescription = "1.3.6.1.2.1.1.1"

    };

    instrumented attribute string sysDescription;

    event Test = sysDescription == "null";

    export Test;

}

Instrumentation is created (with index '0'), no error in logs. Also sm_snmp get returns a valid value for the device. But instrumentation polling doesn't work (greyed out attribute) and get for this attribute gives me the following reason/error:

sudo dmctl * get TestInstrumentation::I-TestInstrumentation-PO-1010-RL-VL-VV/MZ-RC031::sysDescription

SNMP-E-EINVALID-Invalid argument

while the same scenario works without any issue in AMPM.

So, I'm wondering if I'm missing any additional requirement for MPLS.

I've tried changing the index value and oid format in the model file with no result.

Thanks for you help / suggestions.