title: Errors trying to load custom MIB file with pysnmp
body: <p>To interface with a Cordex of Alpha Technologies, I need to use the SNMP protocol. I've been going through the documentation and examples from pysnmp in order to get some aspects working, and I have particular issues when using external MIB files from alpha technologies. My first test was the following: </p>
  
  <pre><code>from pysnmp.hlapi import *
  from pysnmp.smi import builder, view, compiler, rfc1902
  from pysnmp import debug
  #debug.setLogger(debug.Debug('all'))
  debug.setLogger(debug.Debug('msgproc', 'mibbuild'))
  mibBuilder = builder.MibBuilder()
  
  mibViewController = view.MibViewController(mibBuilder)
  test = ObjectIdentity('SNMPv2-MIB', 'sysDescr').addAsn1MibSource('file:///C:/Users/SLN9000/Repositories/cordex/MIB/@mib@')
  test.resolveWithMib(mibViewController)
  test.getOid()
  </code></pre>
  
  <p>when I do this it correctly prints out the correct OID:</p>
  
  <pre><code>&gt;&gt;&gt; ObjectName('1.3.6.1.2.1.1.1')
  </code></pre>
  
  <p>However, when looking at the debug logs, it seems to be using the compiled MIB files from the pysnmp library instead of the ASN.1 files located in "C:/Users/SLN9000/Repositories/cordex/MIB/@mib@".
  When I do something similar for the MIB file from Alpha technologies</p>
  
  <pre><code>from pysnmp.hlapi import *
  from pysnmp.smi import builder, view, compiler, rfc1902
  from pysnmp import debug
  #debug.setLogger(debug.Debug('all'))
  debug.setLogger(debug.Debug('msgproc', 'mibbuild'))
  mibBuilder = builder.MibBuilder()
  
  mibViewController = view.MibViewController(mibBuilder)
  test = ObjectIdentity('03409602D__Alpha_System_Controller', 'dcpower', 1).addAsn1MibSource('file:///C:/Users/SLN9000/Repositories/cordex/MIB/')
  test.resolveWithMib(mibViewController)
  test.getOid()
  </code></pre>
  
  <p>It fails at the step <code>test.resolveWithMib(mibViewController)</code> with the error</p>
  
  <blockquote>
    <p>pysnmp.smi.error.MibNotFoundError: 03409602D__Alpha_System_Controller
    compilation error(s): missing</p>
  </blockquote>
  
  <p>It's not completely clear to me what I am doing wrong. The MIB file I am using can be downloaded from <a href="https://tools.alpha.ca/downloads/docs/03409602D__Alpha_System_Controller_MIB.ZIP" rel="nofollow noreferrer">here</a>. Any help is appreciated!</p>