The file does not exist

Question

I hope you can help me with this problem:

I am trying to add BlogEngine to my existing website by adding the BlogEngine project in a subfolder named "blogs". However, I am stuck with the following error (see below).

The "Site.Master" is placed in the correct folder and correct place in the project

I have,

1. made sure that the security setup on the folder gives access to the user account in the project.
2. tried to change the CodeFile to Codebehind but, I still get this error.

Also, I already have a "Site.Master" in my root directory. Can this be the cause? Is it not capable of differentiating the two .master-sites?

Please help. It drives me crazy!

I built the website in Microsoft Visual Web Developer

 __Server Error in '/' Application.
    --------------------------------------------------------------------------------__
    The file '/themes/Standard/site.master' does not exist. 
    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: System.Web.HttpException: The file '/themes/Standard/site.master' does not  exist.
__
Source Error: 


 An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.  

Stack Trace: 

[HttpException (0x80004005): The file '/themes/Standard/site.master' does not exist.]
   System.Web.UI.Util.CheckVirtualFileExists(VirtualPath virtualPath) +9922708
   System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate) +475
   System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate) +103
   System.Web.UI.MasterPage.CreateMaster(TemplateControl owner, HttpContext context, VirtualPath masterPageFile, IDictionary contentTemplateCollection) +148
   System.Web.UI.Page.get_Master() +54
   System.Web.UI.Page.ApplyMasterPage() +14
   System.Web.UI.Page.PerformPreInit() +45
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +335