Adding a custom Index

[VeeDubbss]

Hi All -

We have an AudioCodes M1000B media gateway and we are trying to track and graph the number of active calls for reporting/trending purposes.  We have the custom MIBs from AudioCodes and have uploaded them into IMC.  I also know the exact OID I want to track.  I have added multiple custom indexes in the past, but this is acting a little different.

I wish to track the acPMTrunkUtilizationVal value with an OID of 1.3.6.1.4.1.5003.10.10.2.21.1.3 (see attached).  When I do a Get it asks me to choose an Index (see attached) and I choose 0.0.  That then brings back the correct value, but the OID is slightly different - 1.3.6.1.4.1.5003.10.10.2.21.1.3.0.0 (notice the additional 0.0 to indicate the selected index) (see attached).

Now, when I go to Global Index Settings --> Add Custom Index and try with the original OID I get a failure and no data collection (see attached).  When I try with the slightly different OID (with the added 0.0), I get an 'Unsupported feature or lack of necessary configuration' message.  

I'm not sure where to go from here to track the data I want.  Again, I've added custom indexes before, but I've never had to deal with choosing from a list of indexes for the OID.

Help?

Thanks!
Max