I'm new to Usync Publisher. I've got a DEV and TEST environment set up on an Azure VM. All I'm trying to sync is content and media, but I'm getting a not-very-helpful error message:

The config is identical on both the DEV and TEST instances of Umbraco:

<?xml version="1.0" encoding="utf-8"?>
<uSyncPublisher incomingEnabled="true" outgoingEnabled="true">
  <!-- incomingEnabled - means this server can be pushed to -->
  <!-- outgoingEnabled - means this server can push content out -->
  <!-- optional - this is an internal name for the server - it is not required 
                    as uSyncPublisher will attempt to work this out from the URL.

                  Can also be overridden with appSettings key 
                  <add key="uSync:Server" value="[serverAlias]" />       
  -->
  <server>Local</server>
  <!-- default mode which lets you share the config between servers -->
  <networkMode>True</networkMode>
  <!-- authentication keys for this server:

    They must match what other servers send this server

    Can also be overridden with appSettings key 

          <add key="uSyncPublish:AppId" value="AppId" />       
          <add key="uSyncPublish:AppKey" value="AppKey" />

    Id/Key generation will be generated first time you
    look at the settings (and they are blank) 
  -->
  <!-- Restart the Application if you change these values here. -->
  <appId>concealed appID for posting here</appId>
  <appKey>concealed appKey for posting here</appKey>
  <!-- /// Send settings -->
  <!-- standard options for whats sent across to a server
        - values are yes, no, user-yes, user-no 
        - user- values are shown at send time
        - can be set per server too 
      -->
  <!-- include the parents of the node -->
  <includeAncestors>no</includeAncestors>
  <!-- include any template files required -->
  <includeFiles>no</includeFiles>
  <!-- include the children of this node -->
  <includeChildren>user-yes</includeChildren>
  <!-- include any media items required for the content -->
  <includeMedia>user-yes</includeMedia>
  <!-- include content linked to from this content -->
  <includeLinked>no</includeLinked>
  <!-- include things like required doctypes, datatypes -->
  <includeDependencies>no</includeDependencies>
  <!-- include media files as part of any sync -->
  <!-- this one is redundant at the moment, as media files are always checked 
       as part of a media sync -->
  <!-- so its not in the UI -->
  <includeMediaFiles>no</includeMediaFiles>
  <!-- delete items from the server not send in the sync (only for folders of items)-->
  <deleteMissing>user-yes</deleteMissing>
  <!-- include the config elements (public access, domain) when syncing content -->
  <includeConfig>yes</includeConfig>
  <!-- default publisher -->
  <publisher>realtime</publisher>
  <!-- /// End send settings -->
  <!-- the groups you need to be in to send (this is all, can be per server) -->
  <groups>admin</groups>
  <!-- which uSync handler set to use (default is publisher) -->
  <handlerSet>publisher</handlerSet>
  <!-- extra folders to check when including files in a sync -->
  <additionalFolders>~/views,~/css,~/scripts</additionalFolders>
  <!-- hide the advanced settings behind a dropdown toggle -->
  <hideAdvanced>True</hideAdvanced>
  <!-- folders to copy when including system files-->
  <systemFolders>~/bin,~/app_plugins</systemFolders>
  <!-- regex pattern to exclude when copying system folders -->
  <!-- uSync will attempt to add your project dll names 
          ie. bin\\myumbraco.site
             but to be certain you should add any custom dll paths you don't want coping here.
    -->
  <systemExclusions>bin\\uSync,app_plugins\\uSync,bin\\App_Data,bin\\FloridaFishAndWildlife\.Core</systemExclusions>
  <!-- default push and pull when you are not on a named sever (below)-->
  <allowedServers>
    <server pull="false" push="true">test-dest</server>
  </allowedServers>
  <servers>
    <!--  you can leave appId and appKey blank, and the global ones
          will be used for all communications or you can have 
          a diffrent appId/Key for each server 
    -->
    <server alias="devOrigin" enabled="true" pullEnabled="true" sortOrder="0" url="https://dev8.myfwc.com/umbraco" showSelf="false">
      <name>DEV (Origin)</name>
      <icon>icon-imac color-blue</icon>
      <description></description>
      <hideAdvanced>False</hideAdvanced>
      <includeMedia>yes</includeMedia>
      <groups>admin</groups>
      <message>Development (Origin)</message>
      <PublisherSettings>
        <canSchedule>true</canSchedule>
        <selectVariants>false</selectVariants>
      </PublisherSettings>
      <allowedServers>
        <server pull="true" push="true">testDestination</server>
      </allowedServers>
      <includeChildren>user-no</includeChildren>
      <deleteMissing>user-no</deleteMissing>
    </server>
    <server alias="testDestination" enabled="true" pullEnabled="true" sortOrder="0" url="https://test8.myfwc.com/umbraco" showSelf="false">
      <name>TEST (Destination)</name>
      <icon>icon-imac color-orange</icon>
      <description></description>
      <hideAdvanced>False</hideAdvanced>
      <includeMedia>yes</includeMedia>
      <groups>admin</groups>
      <allowedServers>
        <server pull="true" push="true">devOrigin</server>
      </allowedServers>
      <message>TEST (Destination)</message>
      <PublisherSettings>
        <canSchedule>true</canSchedule>
        <selectVariants>false</selectVariants>
      </PublisherSettings>
      <includeChildren>user-no</includeChildren>
      <deleteMissing>user-no</deleteMissing>
    </server>
  </servers>
  <message></message>
</uSyncPublisher>

I don't know what else to check.