Sharepoint 2010 部署步骤添加解决方案时出错

我正在开发沙盒解决方案SharePoint 2010（SharePoint在线项目）

我得到的错误是

Error   19  Error occurred in deployment step 'Add Solution': This solution contains invalid markup or elements that cannot be deployed as part of a sandboxed solution. Solution manifest for solution 'c353c02e-f7b0-4c58-b7c6-066adf1d7e0c' failed validation, file manifest.xml, line 3, character 4: The element 'Solution' in namespace 'http://schemas.microsoft.com/sharepoint/' has invalid child element 'CodeAccessSecurity' in namespace 'http://schemas.microsoft.com/sharepoint/'. List of possible elements expected: 'FeatureManifests, Assemblies, ActivationDependencies' in namespace 'http://schemas.microsoft.com/sharepoint/'.
        0   0   Starwood_Forms

VisualStudio中的清单文件（Package.Package）如下所示

<Solution xmlns="http://schemas.microsoft.com/sharepoint/" SolutionId="c353c02e-f7b0-4c58-b7c6-066adf1d7e0c" SharePointProductVersion="14.0">
  <CodeAccessSecurity>
    <PolicyItem>
      <PermissionSet class="NamedPermissionSet" version="1" Description="Permission set for ProjectNameHere.">
        <IPermission class="AspNetHostingPermission" version="1" Level="Minimal" />
        <IPermission class="SecurityPermission" version="1" Flags="Execution,ControlPrincipal,ControlAppDomain,ControlDomainPolicy,ControlEvidence,ControlThread" />
        <IPermission class="Microsoft.SharePoint.Security.SharePointPermission, Microsoft.SharePoint.Security, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" version="1" ObjectModel="True" />
        <IPermission class="System.Security.Permissions.EnvironmentPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Read="UserName" />
        <IPermission class="System.Security.Permissions.FileIOPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Read="$AppDir$" Write="$AppDir$" Append="$AppDir$" PathDiscovery="$AppDir$" />
      </PermissionSet>
      <Assemblies>
        <Assembly Name="ProjectNameHere" />
      </Assemblies>
    </PolicyItem>
  </CodeAccessSecurity>
  <Assemblies>
    <Assembly Location="ProjectNameHere.dll" DeploymentTarget="GlobalAssemblyCache">
      <SafeControls>
        <SafeControl Assembly="ProjectNameHere, Version=1.0.0.0, Culture=neutral, PublicKeyToken=7e39ecec9e69afb4" Namespace="ProjectNameHereWebPart" TypeName="*" />
      </SafeControls>
    </Assembly>
  </Assemblies>
  <FeatureManifests>
    <FeatureManifest Location="ProjectNameHere_Feature2\Feature.xml" />
  </FeatureManifests>
</Solution>

当代码试图创建一个新的列表项时，我得到了上面的错误

我正在使用沙盒可视web部件

---

如果我从“解决方案”中删除“CodeAccessSecurity”子元素，但我无法创建新的列表项，则该解决方案将被激活，不会出现任何问题。我正在使用LINQ to SharePoint创建一个新的列表项

如果我不使用数据上下文来创建新的列表项，那么下面的代码可以很好地工作

 SPList list = objWeb.Lists.TryGetList("ListName");
                        SPListItem newListItem = list.AddItem();
                        newListItem["Department"] = new SPFieldLookupValue(int.Parse(ddlDepartment.SelectedValue), ddlDepartment.SelectedItem.Text);

                        newListItem.Update();

如果你有任何其他想法，请让我知道

 SPList list = objWeb.Lists.TryGetList("ListName");
                        SPListItem newListItem = list.AddItem();
                        newListItem["Department"] = new SPFieldLookupValue(int.Parse(ddlDepartment.SelectedValue), ddlDepartment.SelectedItem.Text);

                        newListItem.Update();