添加用户控件缓存依赖项发生的异常？高手指正。

无法在配置中找到“MSPetShop4”数据库。 
说明: 执行当前 Web 请求期间，出现未处理的异常。请检查堆栈跟踪信息，以了解有关该错误以及代码中导致错误的出处的详细信息。 异常详细信息: System.Web.HttpException: 无法在配置中找到“MSPetShop4”数据库。源错误: 
行 21:             foreach (String table in tables) {
行 22:                 //{"无法在配置中找到“MSPetShop4”数据库。"}
行 23:                 cacheDependence.Add(new SqlCacheDependency(DBName, table));
行 24:             }
行 25:            
 源文件: D:\zhangzhiguo\Projects\TableDependence\TableCacheDependence\TableDependence.cs    行: 23 堆栈跟踪: 
[HttpException (0x80004005): 无法在配置中找到“MSPetShop4”数据库。]
   System.Web.Caching.SqlCacheDependencyManager.GetDatabaseConfig(String database) +2589429
   System.Web.Caching.SqlCacheDependencyManager.InitPolling(String database) +71
   System.Web.Caching.SqlCacheDependencyManager.EnsureTableIsRegisteredAndPolled(String database, String table) +91
   System.Web.Caching.SqlCacheDependency.GetDependKey(String database, String tableName) +60
   System.Web.Caching.SqlCacheDependency..ctor(String databaseEntryName, String tableName) +37
   PetShop.TableDependence.TableCacheDependece..ctor(String tableConfigKey) in D:\zhangzhiguo\Projects\TableDependence\TableCacheDependence\TableDependence.cs:23
   PetShop.TableDependence.Category..ctor() in D:\zhangzhiguo\Projects\TableDependence\TableCacheDependence\Category.cs:10[TargetInvocationException: 调用的目标发生了异常。]
   System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandle& ctor, Boolean& bNeedSecurityCheck) +0
   System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean fillCache) +86
   System.RuntimeType.CreateInstanceImpl(Boolean publicOnly, Boolean skipVisibilityChecks, Boolean fillCache) +230
   System.Activator.CreateInstance(Type type, Boolean nonPublic) +67
   System.RuntimeType.CreateInstanceImpl(BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes) +1051
   System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes) +111
   System.Reflection.Assembly.CreateInstance(String typeName, Boolean ignoreCase, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes) +61
   System.Reflection.Assembly.CreateInstance(String typeName) +16
   PetShop.CacheDependenceFactory.CacheDependenceAccess.LoadInstance(String path) in D:\zhangzhiguo\Projects\CacheDependence\CacheDependenceFactory\CacheDependenceAccess.cs:23
   PetShop.CacheDependenceFactory.CacheDependenceAccess.GetCategoryCacheDependence() in D:\zhangzhiguo\Projects\CacheDependence\CacheDependenceFactory\CacheDependenceAccess.cs:15
   PetShop.CacheDependenceFactory.DependenceFacade.GetCategoryCacheDependence() in D:\zhangzhiguo\Projects\CacheDependence\CacheDependenceFactory\DependenceFacade.cs:18
   Controls_NavigationControl.Page_Load(Object sender, EventArgs e) in d:\zhangzhiguo\WEB\UpdatePetShop\Controls\NavigationControl.ascx.cs:39
   System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35
   System.Web.UI.Control.OnLoad(EventArgs e) +99
   System.Web.UI.Control.LoadRecursive() +50
   System.Web.UI.Control.LoadRecursive() +141
   System.Web.UI.BasePartialCachingControl.LoadRecursive() +45
   System.Web.UI.Control.LoadRecursive() +141
   System.Web.UI.Control.LoadRecursive() +141
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +627{"调用的目标发生了异常。"}{"无法在配置中找到“MSPetShop4”数据库。"} 
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版本信息: Microsoft .NET Framework 版本:2.0.50727.3603; ASP.NET 版本:2.0.50727.3614