winform 用Log4net将日志写入数据库

从网上复制的代码 步骤按照上面的来写的 数据库也和他建的一样 数据库连接字符串被我改过来了
但是还是出现报错

下面是我的代码
log4net.config文件

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <section name="log4net" type="System.Configuration.IgnoreSectionHandler,log4net"/>
  </configSections>
  <log4net>
    <!--定义输出到数据库中，这里举例输出到sql server数据库中-->
    <appender  ="AdoNetAppender" type="log4net.Appender.AdoNetAppender">
      <bufferSize value="1" />
      <!--数据库类型-->
      <connectionType value="System.Data.SqlClient.SqlConnection, System.Data, Version=4.0.0.0,Culture=neutral, PublicKeyToken=b77a5c561934e089"/>
      <!--数据库连接串-->
      <connectionString value="Data Source=.;Initial Catalog=User;Integrated Security=True" />
      <!--日志插入数据语句-->
      <commandText value="INSERT INTO Log4netInfo ([GUID],[LOG_DATE],[THREAD],[LEVEL],[LOGGER],[MESSAGE],[EXCEPTION]) VALUES (newid(),@logDate, @thread, @logLevel, @logger,@message,@exception)"  />
      <!--定义各个参数-->
      <parameter>
        <parameterName value="@logDate"  />
        <dbType value="String"  />
        <size value="240"  />
        <layout type="log4net.Layout.RawTimeStampLayout">
          <conversionPattern value="%date"  />
        </layout>
      </parameter>
      <parameter>
        <parameterName value="@thread"  />
        <dbType value="String"  />
        <size value="240"  />
        <layout type="log4net.Layout.PatternLayout">
          <conversionPattern value="%thread"  />
        </layout>
      </parameter>
      <parameter>
        <parameterName value="@logLevel"  />
        <dbType value="String"  />
        <size value="240"  />
        <layout type="log4net.Layout.PatternLayout">
          <conversionPattern value="%level"  />
        </layout>
      </parameter>
      <parameter>
        <parameterName value="@logger"  />
        <dbType value="String"  />
        <size value="240"  />
        <layout type="log4net.Layout.PatternLayout">
          <conversionPattern value="%logger"  />
        </layout>
      </parameter>
      <parameter>
        <parameterName value="@message"  />
        <dbType value="String"  />
        <size value="4000"  />
        <layout type="log4net.Layout.PatternLayout">
          <conversionPattern value="%message"  />
        </layout>
      </parameter>
      <parameter>
        <parameterName value="@exception" />
        <dbType value="String" />
        <size value="4000" />
        <layout type="log4net.Layout.ExceptionLayout" />
      </parameter>
    </appender>
    <!--定义日志的输出媒介-->
    <root>
      <!-- 启用相应的日志记录-->
      <appender-ref  ="AdoNetAppender" />
      <!--日志记录级别-->
      <level value="Error" />
    </root>
  </log4net>
  
</configuration>