That appears to be the issue, there is no channel type of ‘dimmer’ available in MQTT binding as far as I can see in the dropdown list?
<md-select-menu class="ng-scope md-overflow" style="transform-origin: 221.789px 24px 0px;"><md-content>
<!-- ngRepeat: channelType in channelTypes --><md-option ng-repeat="channelType in channelTypes" ng-value="channelType" tabindex="0" class="ng-scope md-ink-ripple" role="option" aria-selected="false" id="select_option_7" aria-checked="true" value="[object Object]" style=""><div class="md-text">
<span class="md-caption ng-binding">Text Value</span>
</div></md-option><!-- end ngRepeat: channelType in channelTypes --><md-option ng-repeat="channelType in channelTypes" ng-value="channelType" tabindex="0" class="ng-scope md-ink-ripple" role="option" aria-selected="false" id="select_option_8" aria-checked="true" value="[object Object]"><div class="md-text">
<span class="md-caption ng-binding">Number Value</span>
</div></md-option><!-- end ngRepeat: channelType in channelTypes --><md-option ng-repeat="channelType in channelTypes" ng-value="channelType" tabindex="0" class="ng-scope md-ink-ripple" role="option" aria-selected="false" id="select_option_9" aria-checked="true" value="[object Object]"><div class="md-text">
<span class="md-caption ng-binding">Percentage Value</span>
</div></md-option><!-- end ngRepeat: channelType in channelTypes --><md-option ng-repeat="channelType in channelTypes" ng-value="channelType" tabindex="0" class="ng-scope md-ink-ripple" role="option" aria-selected="false" id="select_option_10" aria-checked="true" value="[object Object]"><div class="md-text">
<span class="md-caption ng-binding">On/Off Switch</span>
</div></md-option><!-- end ngRepeat: channelType in channelTypes --><md-option ng-repeat="channelType in channelTypes" ng-value="channelType" tabindex="0" class="ng-scope md-ink-ripple" role="option" aria-selected="false" id="select_option_11" aria-checked="true" value="[object Object]"><div class="md-text">
<span class="md-caption ng-binding">Open/Close Contact</span>
</div></md-option><!-- end ngRepeat: channelType in channelTypes --><md-option ng-repeat="channelType in channelTypes" ng-value="channelType" tabindex="0" class="ng-scope md-ink-ripple" role="option" aria-selected="false" id="select_option_12" aria-checked="true" value="[object Object]"><div class="md-text">
<span class="md-caption ng-binding">Color Value (Red,Green,Blue)</span>
</div></md-option><!-- end ngRepeat: channelType in channelTypes --><md-option ng-repeat="channelType in channelTypes" ng-value="channelType" tabindex="0" class="ng-scope md-ink-ripple" role="option" aria-selected="false" id="select_option_13" aria-checked="true" value="[object Object]"><div class="md-text">
<span class="md-caption ng-binding">Color Value (Hue,Saturation,Brightness)</span>
</div></md-option><!-- end ngRepeat: channelType in channelTypes --><md-option ng-repeat="channelType in channelTypes" ng-value="channelType" tabindex="0" class="ng-scope md-ink-ripple" role="option" aria-selected="false" id="select_option_14" aria-checked="true" value="[object Object]"><div class="md-text">
<span class="md-caption ng-binding">Date/Time Value</span>
</div></md-option><!-- end ngRepeat: channelType in channelTypes --><md-option ng-repeat="channelType in channelTypes" ng-value="channelType" tabindex="0" class="ng-scope md-ink-ripple" role="option" aria-selected="false" id="select_option_15" aria-checked="true" value="[object Object]"><div class="md-text">
<span class="md-caption ng-binding">Image</span>
</div></md-option><!-- end ngRepeat: channelType in channelTypes --><md-option ng-repeat="channelType in channelTypes" ng-value="channelType" tabindex="0" class="ng-scope md-ink-ripple" role="option" aria-selected="false" id="select_option_16" aria-checked="true" value="[object Object]"><div class="md-text">
<span class="md-caption ng-binding">Location</span>
</div></md-option><!-- end ngRepeat: channelType in channelTypes --><md-option ng-repeat="channelType in channelTypes" ng-value="channelType" tabindex="0" class="ng-scope md-ink-ripple" role="option" aria-selected="false" id="select_option_17" aria-checked="true" value="[object Object]"><div class="md-text">
<span class="md-caption ng-binding">Rollershutter</span>
</div></md-option><!-- end ngRepeat: channelType in channelTypes -->
</md-content></md-select-menu>