Rename Folder (Directory) name in FTP Server using C# in ASP.Net

Hello friends,

i ll trying to rename folder inside ftp from 52 to 54 but not wokring pls help

 string dir = "27";
 string usercode = "Crisi";
 string pwd ="123";
 string ftp ="ftp://smr-test.papers.com/ALG/Files/DocumentModule/DefectIdentification/27/Mismatch/52";
FtpWebRequest request = (FtpWebRequest)WebRequest.Create(ftp); 
request.Method = WebRequestMethods.Ftp.Rename; 
request.Credentials = new NetworkCredential(usercode, pwd);
request.RenameTo = "ftp://smr-test.papers.com/ALG/Files/DocumentModule/DefectIdentification/27/Mismatch/54";