问Dotless编译器退出，返回代码-1 - MSBuild

EN

<?xml version="1.0" encoding="utf-8" ?>
<Project xmlns="http://schemas.microsoft.com/developer/MsBuild/2003">
  <!--    
    This MSBuild Script will compile all [*.less] files in the /CSS folder to their [*.min.css] counterparts.
    -->
  <ItemGroup>
    <LessFiles Include="Styles\*.less" />
  </ItemGroup>
  <Target Name="CompileDotlessCss" AfterTargets="AfterBuild">
    <ItemGroup>
      <Binaries Include="*.dll;*.exe"/>
    </ItemGroup>

    <!-- Compile dotLess CSS into minified full CSS -->
    <Exec Command="[MSBuild]\dotless.compiler.exe -m %(LessFiles.FullPath)  $([System.String]::Copy('%(LessFiles.FullPath)').Replace('.less','.min.css'))" />

  </Target>
</Project>

The command "[MSBuild]\dotless.compiler.exe -m C:\Source Control\MyProject\MyProject.Web\Styles\main.less  C:\Source Control\MyProject\MyProject.Web\Styles\main.min.css" exited with code -1.