web.config doesn't support "+" or Server.MapPath, try<add key="sqlconnstringProvider" value="Microsoft.Jet.OLEDB.4.0;"/>
<add key="sqlconnstringDataSource" value="/mynss/data/db.mdb"/>then in your code, you dostring sConn = String.Format("Provider={0};Data Source={1};", ConfigurationSettings.AppSettings["sqlconnstringProvider"], Server.MapPath(ConfigurationSettings.AppSettings["sqlconnstringDataSource"]));

解决方案 »

  1.   

    <add key="sqlconnstring" value="Provider=Microsoft.Jet.OLEDB.4.0;Data Source="+Server.MapPath("/mynss/data/db.mdb") />
      

  2.   

    或是webconfig中:
    <add key="OleDBConnString" value="/webAdmin/RencaiAdmin/DB/db.mdb" />
    应用程序中:
     CONN_STRING = "Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" + System.Web.HttpContext.Current.Server.MapPath(ConfigurationSettings.AppSettings["OleDBConnString"])