Log4net error coming

Hi, we have visual studio 2010 and crystal report installed. when i run it in local pc it is working but when i publish the website then i get error : Server Error in '/' Application. Could not load file or assembly 'log4net, Version=1.2.10.0, Culture=neutral, PublicKeyToken=692fbea5521e1304' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040) Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: [login to view URL]: Could not load file or assembly 'log4net, Version=1.2.10.0, Culture=neutral, PublicKeyToken=692fbea5521e1304' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040) Source Error: The source code that generated this unhandled exception can only be shown when compiled in debug mode. To enable this, please follow one of the below steps, then request the URL: 1. Add a "Debug=true" directive at the top of the file that generated the error. Example: <%@ Page Language="C#" Debug="true" %> or: 2) Add the following section to the configuration file of your application: <configuration> <[login to view URL]> <compilation debug="true"/> </[login to view URL]> </configuration> Note that this second technique will cause all files within a given application to be compiled in debug mode. The first technique will cause only that particular file to be compiled in debug mode. Important: Running applications in debug mode does incur a memory/performance overhead. You should make sure that an application has debugging disabled before deploying into production scenario. Assembly Load Trace: The following information can be helpful to determine why the assembly 'log4net, Version=1.2.10.0, Culture=neutral, PublicKeyToken=692fbea5521e1304' could not be loaded. WRN: Assembly binding logging is turned OFF. To enable assembly bind failure logging, set the registry value [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1. Note: There is some performance penalty associated with assembly bind failure logging. To turn this feature off, remove the registry value [HKLM\Software\Microsoft\Fusion!EnableLog]. Stack Trace: [FileLoadException: Could not load file or assembly 'log4net, Version=1.2.10.0, Culture=neutral, PublicKeyToken=692fbea5521e1304' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)] CrystalDecisions.Web.CrystalReportViewer..cctor() +0 [TypeInitializationException: The type initializer for '[login to view URL]' threw an exception.] CrystalDecisions.Web.CrystalReportViewer..ctor() +0 ASP.reportpreviewfrom_aspx.__BuildControlCrystalReportViewer1() +27 ASP.reportpreviewfrom_aspx.__BuildControlContent1(Control __ctrl) +52 [login to view URL](Control container) +12 ASP.main_master.__BuildControlContentPlaceHolder1() +104 ASP.main_master.__BuildControlform1() +90 ASP.main_master.__BuildControlTree(main_master __ctrl) +71 [login to view URL]() +37 [login to view URL]() +35 [login to view URL](TemplateControl owner, HttpContext context, VirtualPath masterPageFile, IDictionary contentTemplateCollection) +8760447 System.Web.UI.Page.get_Master() +51 [login to view URL]() +15 [login to view URL]() +45 [login to view URL](Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +282 Version Information: Microsoft .NET Framework Version:2.0.50727.5485; ASP.NET Version:2.0.50727.5483