.net – Why doesn’t MSBuild copy as I would expect

I'm needing to script my build. I'm using MSBUILD because of it's integration with VS.net. I am trying to copy some files from the build environment to the deployment folder. I'm using the copy task of MSBuild. But instead of copying the directory tree as I would expect. it copies all the contents into a single folder. I repeat all the files from the directory tree end up in one folder. I need it to copy the tree of folders and directories into the destination folder. Is there something I'm missing?

Here is the relavant parts of my build script:

<PropertyGroup>
    <TargetFrameworkVersion>v2.0</TargetFrameworkVersion>
    <Source>outputfolder</Source>
    <DestEnv>x</DestEnv>
    <DeployPath>\\networkpath\$(DestEnv)</DeployPath>
</PropertyGroup>
<ItemGroup>
    <TargetDir Include="$(DeployPath)\**\*" Exclude="**\web.config"></TargetDir>
    <SourceDir Include="$(Source)\**\*" />
</ItemGroup>    
<Target Name="Clean" >
    <!-- clean detail ... -->
</Target>
<Target Name="migrate" DependsOnTargets="Clean">
    <Copy DestinationFolder="$(DeployPath)" SourceFiles="@(SourceDir)" />
</Target>