Proxy user sessions from ASP.Net never released to the Connection Pool
First I made check from login page if txt_user_name/txt_user_password enterd is an authincating oracle user
String ConnStr = "DATA SOURCE=mydb;PASSWORD=" + txt_user_password +
";PERSIST SECURITY INFO=False;USER ID=" + txt_user_name +
";Proxy User Id=portal;Proxy Password=Stud#ProxY" +
";Min Pool Size=50;Max Pool Size=500;Connection Lifetime=0;Connection Timeout=120;"