Custom Plugin not showing under admin Local Plugins

Its not working Now I tried with versoin 4.0 having same problem my custom plugin not showing under admin listing.

My source code under plugin folder at root and after build it generate dll etc  at location Presentation\Nop.Web\Plugins\Url.Redirect

Now when debug  the code I get the following error.

maingPluginFile become null for my custom plugin in  and condition plugin have wrong directory executed. my plugin setting are perfectly same as other built in plugin have.

//plugin have wrong directory
if (mainPluginFile == null)
                            {
                                incompatiblePlugins.Add(pluginDescriptor.SystemName);
                                continue;
                            }

P.S> No need to start new threads
See https://www.nopcommerce.com/en/boards/topic/91908/custom-plugin-not-showing-under-admin-local-plugins/page/2
and https://www.nopcommerce.com/en/boards/topic/91926/my-custom-plugin-have-wrong-directory-error-and-not-showing-under-admin-local-plugins