A reference to “ .dll” this could not be added

Question

In a project within my solution I have the following code to generate a .dll assembly. Developed mainly with the msdn documentation and the answer to another question here on stackoverflow . The code builds and runs fine and the ".dll" assembly in generated in the bin\\debug folder within the project. However I have problems referencing the assembly in other projects within the solution. I right click references-> add reference and select the ".dll" file. When I click ok I get the error message stated in the title of this question. Thanks.

        // Retrieve application domain ie environment where applications execute
        // This is done because if an assembly is loaded into the default 
        // application domain it cannot be unloaded from memory while the process
        // is running. However if another application domain is opened to load
        // and execute the assembly, the assembly is unloaded when the application
        // domain is unloaded. 
        AppDomain currentDomain = AppDomain.CurrentDomain;

        // Now create a dynamic assembly in the current application domain
        // and allow it to be executed and saved to disk
        AssemblyName name = new AssemblyName("FieldIdEnum");
        AssemblyBuilder assemblyBuilder = currentDomain.DefineDynamicAssembly(name,
            AssemblyBuilderAccess.RunAndSave);

        // Now we define a dynamic module in the assembly that was just created
        // For this single single module assembly the module has the same name as 
        // the assembly
        ModuleBuilder moduleBuilder = assemblyBuilder.DefineDynamicModule(name.Name,
            name.Name + ".dll");

        // Now we define the public enumeration with the name "DbFieldId" and an
        // underlying type of Integer
        EnumBuilder myEnumBuilder = moduleBuilder.DefineEnum("EnumeratedTypes.DbFieldId",
            TypeAttributes.Public, typeof(int));

        // Now retrieve the FieldId table from the database, bear in mind that the
        // string description will have white spaces, these need to be trimmed 
        // otherwise they are invalid for enum
        // For this to work a reference was added to ConsoleApplication4 and
        // Entity Framework
        using (FieldIdEntities dbEntities = new FieldIdEntities())
        {
            var lines = dbEntities.CSV_FIELD_DETAILS;
            foreach (var field in lines)
            {
                myEnumBuilder.DefineLiteral(field.DESCRIPTION.Replace(" ", String.Empty),               (int)field.FIELD_ID);
            }
        }

        // Now create the enum
        myEnumBuilder.CreateType();

        // If good so far save the assembly:
        assemblyBuilder.Save(name.Name + "dll");

Answer 1

Did you try adding the project containing the DLL into the same solution and then in the reference manager select

Solution -> Projects -> [your dll project]

so that visual studio adds the appropriate dll itself?