这是完整的错误代码：
[2013-03-20 15:34:52,901] Sync3DCartDatabase.ConfigHandler - System.NullReferenceException：对象引用未设置为对象的实例。在 Sync3DCartDatabase.ConfigHandler.Create（对象父，对象 configContext，XmlNode 部分）
[错误] [2013-03-20 15:34:52,917] ASP.syncdatabase_aspx - System.NullReferenceException：对象引用未设置为对象的实例。在 Sync3DCartDatabase.SyncDatabase.SyncDatabaseFromFile()
下面是看起来正在引用的代码的一部分。如果需要，我可以发布整个代码。
<?xml version="1.0"?>
<!--
For more information on how to configure your ASP.NET application, please visit
http://go.microsoft.com/fwlink/?LinkId=169433
-->
<configuration>
<configSections>
<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net"/>
<sectionGroup name="SyncServiceConfigSection">
<section name="ServiceConfig" type="Sync3DCartDatabase.ConfigHandler, Sync3DCartDatabase" />
</sectionGroup>
</configSections>
<log4net>
<appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender">
<file value="logfile.txt" />
<appendToFile value="true" />
<rollingStyle value="Size" />
<maxSizeRollBackups value="5" />
<maximumFileSize value="1MB" />
<staticLogFileName value="true" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="[%level] [%date] %logger - %message%newline" />
</layout>
</appender>
<root>
<level value="INFO" />
<appender-ref ref="RollingFileAppender" />
</root>
</log4net>
<SyncServiceConfigSection>
<ServiceConfig>
<!--Time Interval after which to Sync Database (in secs)-->
<SyncInterval>2700</SyncInterval>
<!--Path where working files will be placed-->
<WorkingFolder>FTPHelperFolder</WorkingFolder>
<SourceFolderPath>/wwwroot/flatfile</SourceFolderPath>
<CartConnectionInfo>
<StoreUrl>Store URL Here</StoreUrl>
<UserKey>API Key Here</UserKey>
</CartConnectionInfo>
<!--FTP Machine information to connect-->
<FTPSessionOptionInfo>
<HostName>FTP Host Here</HostName>
<PortNumber>-1</PortNumber>
<UserName>FTP User</UserName>
<Password>FTP Pass</Password>
<!--FTP = 0, SFTP = 1-->
<FTPProtocol>0</FTPProtocol>
<SshHostKeyFingerprint></SshHostKeyFingerprint>
<!-- None = 0, Implicit = 1, ExplicitSsl = 2, ExplicitTls = 3-->
<FTPSecure>0</FTPSecure>
<SslHostCertificateFingerprint>SSL Finger</SslHostCertificateFingerprint>
</FTPSessionOptionInfo>
<MappedFileDetails>
<MappedFileDetails>
<FileInfo fileNameSuffix="P" fileNamePattern="yyyyMMdd" fileExtension=".txt" >
<!-- Delete the file after it has been successfully updated to 3D cart-->
<!-- 0= Do Not Delete / 1 = Delete-->
<DeleteFTPFileAfterSync>0</DeleteFTPFileAfterSync>
<!--Mapping for input and output column names-->
<ColumnsMappingDetails>
<ColumnsMappingDetails>
<column name="SKU" mappedName="id" update="0" insert="1" ColumnType="2"></column>
<column name="STATUS 0=ACTIVE/9=INACTIVE" mappedName="hide" update="0" ColumnType="3" insert="0">
<!--Mapping for input to output column values-->
<MappedValues>
<value origValue="0" mappedValue="0"></value>
<value origValue="9" mappedValue="1"></value>
</MappedValues>
</column>
<column name="QTY AVAILABLE" mappedName="Stock" update="0" insert="0" ColumnType="1"></column>
<column name="STYLE" mappedName="mfgid" update="0" insert="0" ColumnType="2"></column>
<column name="SUGG PRICE" mappedName="price2" update="0" insert="0" ColumnType="1"></column>
<column name="PRICE" mappedName="price" update="1" insert="1" ColumnType="4"></column>
<column name="ADVERTIZED PRICE" mappedName="saleprice" update="1" insert="1" ColumnType="4"></column>
</ColumnsMappingDetails>
</ColumnsMappingDetails>
</FileInfo>
<FileInfo fileNameSuffix="S" fileNamePattern="yyyyMMdd" fileExtension=".txt" >
<!-- Delete the file after it has been successfully updated to 3D cart-->
<!-- 0= Do Not Delete / 1 = Delete-->
<DeleteFTPFileAfterSync>0</DeleteFTPFileAfterSync>
<!--Mapping for input and output column names-->
<ColumnsMappingDetails>
<ColumnsMappingDetails>
<column name="SKU" mappedName="id" update="0" insert="1" ColumnType="2"></column>
<column name=" SET PRICE" mappedName="price" update="1" insert="1" ColumnType="4"></column>
<column name="ADVERTIZED SET PRICE" mappedName="saleprice" update="1" insert="1" ColumnType="4"></column>
</ColumnsMappingDetails>
</ColumnsMappingDetails>
</FileInfo>
</MappedFileDetails>
</MappedFileDetails>
</ServiceConfig>
</SyncServiceConfigSection>
<system.web>
<compilation debug="true" targetFramework="4.0" />
<customErrors mode="Off"/>
<authentication mode="Forms">
<forms loginUrl="~/Account/Login.aspx" timeout="2880" />
</authentication>
<membership>
<providers>
<clear/>
<add name="AspNetSqlMembershipProvider" type="System.Web.Security.SqlMembershipProvider" connectionStringName="ApplicationServices"
enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" requiresUniqueEmail="false"
maxInvalidPasswordAttempts="5" minRequiredPasswordLength="6" minRequiredNonalphanumericCharacters="0" passwordAttemptWindow="10"
applicationName="/" />
</providers>
</membership>
<profile>
<providers>
<clear/>
<add name="AspNetSqlProfileProvider" type="System.Web.Profile.SqlProfileProvider" connectionStringName="ApplicationServices" applicationName="/"/>
</providers>
</profile>
<roleManager enabled="false">
<providers>
<clear/>
<add name="AspNetSqlRoleProvider" type="System.Web.Security.SqlRoleProvider" connectionStringName="ApplicationServices" applicationName="/" />
<add name="AspNetWindowsTokenRoleProvider" type="System.Web.Security.WindowsTokenRoleProvider" applicationName="/" />
</providers>
</roleManager>
</system.web>
<system.webServer>
<modules runAllManagedModulesForAllRequests="true"/>
</system.webServer>
<system.serviceModel>
<bindings>
<basicHttpBinding>
<binding name="cartAPISoap" />
<binding name="cartAPIAdvancedSoap" />
</basicHttpBinding>
</bindings>
<client>
<endpoint address="http://api.3dcart.com/cart_advanced.asmx"
binding="basicHttpBinding" bindingConfiguration="cartAPISoap"
contract="cartAPI.cartAPISoap" name="cartAPISoap" />
<endpoint address="http://api.3dcart.com/cart_advanced.asmx"
binding="basicHttpBinding" bindingConfiguration="cartAPIAdvancedSoap"
contract="cartAPI.cartAPIAdvancedSoap" name="cartAPIAdvancedSoap" />
</client>
</system.serviceModel>
</configuration>