Error occurred while connecting to the ftp server: 451 UnExpected reply code Failure writing to local file

Hi,

   I am trying to write a file into legacy system from SAP through PI(File Adapter). Got the given below error message, please suggest where would be the problem. I checked with unix team who takes care of ftp server. They confirmed that user account can do remote logins, and no it is not an admin account. Also they are able to ftp files too.

Error message: " Error occurred while connecting to the ftp server : severname

                                  Error during STOR/APPE epilogue:

                                  451 UnExpected reply code Failure writing to local file". 

In communication channel, tried to test "Ping Channel". It gives me "FTP Connection test error {0} and {1} cannot be created"

Thanks in advance.

Regards

Rupa