Eric, Flex Viewer and/or Widget Questions belong in the Flex Viewer Forum and not here in the Flex API forum:Flex Viewer forum:http://forums.arcgis.com/forums/111-ArcGIS-Viewer-for-FlexHere is the complete main config.xml for viewing that wms service. You need to be aware that the service is in EPSG:4269 and thus is not going to work with esri tiled basemaps, so I made streetmap dynamic.<?xml version="1.0" ?>
<!--
////////////////////////////////////////////////////////////////////////////////
//
// Read more about ArcGIS Viewer for Flex - http://links.esri.com/flexviewer
//
////////////////////////////////////////////////////////////////////////////////
-->
<configuration>
<title>ArcGIS Viewer for Flex</title>
<subtitle>a configurable web mapping application</subtitle>
<logo>assets/images/logo.png</logo>
<style>
<colors>0xFFFFFF,0x333333,0x101010,0x000000,0xFFD700</colors>
<alpha>0.8</alpha>
</style>
<!-- replace the following url with your own geometryservice -->
<geometryservice url="http://tasks.arcgisonline.com/ArcGIS/rest/services/Geometry/GeometryServer" />
<!-- UI elements -->
<widget left="10" top="50" config="widgets/Navigation/NavigationWidget.xml" url="widgets/Navigation/NavigationWidget.swf"/>
<widget right="-2" bottom="-2" config="widgets/OverviewMap/OverviewMapWidget.xml" url="widgets/OverviewMap/OverviewMapWidget.swf"/>
<widget right="20" top="55" config="widgets/MapSwitcher/MapSwitcherWidget.xml" url="widgets/MapSwitcher/MapSwitcherWidget.swf"/>
<widget left="0" top="0" config="widgets/HeaderController/HeaderControllerWidget.xml" url="widgets/HeaderController/HeaderControllerWidget.swf"/>
<map wraparound180="true" top="40" wkid="4269" units="{Units.DECIMAL_DEGREES}" initialextent="-125.000000 24.650000 -66.800000 49.500000">
<basemaps>
<layer label="Streets" type="dynamic" visible="true" alpha="1" imageformat="jpg" dpi="96"
url="http://server.arcgisonline.com/ArcGIS/rest/services/ESRI_StreetMap_World_2D/MapServer"/>
</basemaps>
<operationallayers>
<layer label="Current MODIS Fire Detection Locations" type="wms"
skipgetcapabilities="true"
url="http://activefiremaps.fs.fed.us/cgi-bin/mapserv.exe?map=conus.map&SERVICE=WMS"
version="1.1.1"
visible="true"
visiblelayers="Current Large incidents,Cities,Capital Cities,Roads,Last 6 hour fire detections,Last 12 hour fire detections,Last 24 hour fire detections,Cumulative Fire Detections"/>
</operationallayers>
</map>
<!-- widgets organized into widget containers that manage close/open etc -->
<!-- supported layout property options: horizontal(default)|float|vertical|fix-->
<widgetcontainer layout="float">
</widgetcontainer>
</configuration>
Don't forget to click the Mark as answer check on this post and to click the top arrow (promote).Follow the steps as shown in the below graphic: