Running vCenter Operations 5.7 vApp. Grabbed the third-party SNMP adapter via ftp://ftp.integrien.com/ and installed the pak file via the update tab of the admin website.
Logged into the custom site, and from admin->support, clicked on the describe icon. Adapter showed up fine, version 5.
Copied a MIB to the vApp in /usr/lib/vmware-vcops/user/plugins/inbound/snmp_adapter3/conf/mibs/ directory and ran the updateMibs.sh script. Checked the mib-import.log (no errors) and verified mib added to mib-imports.props file. Edited the describe.xml file and incremented the version to 6 as indicated in the docs.
Went back to admin->support and clicked the describe icon, but my adapter version is not incrementing to 6, and I do not see my MIB in the pulldown when adding a resource.
I've restarted everything, but vCenter is not picking up my changes. Can someone explain what I'm doing wrong? 
Thanks!
Accepted Solutions
Aaaand, no, I was not 
how silly is that?
I really need to get these machines renamed. Thank you for that excellent follow-up question!