How can i add vb.net dll into c# application

I have develop one application in C# windows in this i need to add vb.net dll files.I have try add dll files from source->add References.But,i am getting error

   **Could not find the dll files **

Because i am adding the dll files (assembly1 into assembly**2 and **assembly2 into assembly3 )

** New Code **

C:\Program Files (x86)\Microsoft\ILMerge>ilmerge /t:dll /out:ExcelImportnew.dll ExcelImport.dll BOL.dll

An exception occurred during merging:

      Access to the path 'C:\Program Files (x86)\Microsoft\ILMerge\ExcelImportnew.dll' is denied.
       at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
          at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolea
         useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, Sring msgPath, Boolean bFromProxy)
               at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, In32 bufferSize, FileOptions options, String msgPath, Boolean bFromProxy)
            at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share)
            at System.Compiler.Writer.WritePE(String location, Boolean writeDebugSymbols, Module module, Boolean delaySign, String keyFileName, String keyName)
             at System.Compiler.Writer.WritePE(CompilerParameters compilerParameters, Module module)
           at ILMerging.ILMerge.Merge()
            at ILMerging.ILMerge.Main(String[] args)

Please tell me why i am getting this error.How can i resolve this error. Thanks !

Solution

Have you tried to combine the dll's with ILMerge?

ilmerge /target:library /out:YourLib.dll ClassLibrary1.dll ClassLibrary2.dll