Check if a file exist in the Server in ASP.NET

        string jSFile = ResolveUrl("~/MyProject/JavaScripts/dir/test.js");
        if (!System.IO.File.Exists(jSFile))
        {
           ...
        }

This code doesn't work and I guess it's the jSFile that doesn't work well with the IO.File.Exists but I know the jSFile has a valid path because when I use few line later

Page.ClientScript.RegisterClientScriptInclude("myfile",jS开发者_开发知识库File); 

it does attach the JavaScript file to the ASPX and all work fine.

Any idea of how to check if the file exist?

if (!System.IO.File.Exists(Server.MapPath(jSFile)))