Could you please give some idea regarding the below issue:

We want to execute one shell script to pick the file from FTP server through SFTP connection. Through FTP connection we are able to pick and move the file to target folder but through SFTP we can't. We are unable to run the script through BODS. is there any connect issue or any command issue??Its giving the below error:

 1: spawn /usr/bin/sftp -o Port=22 BWFTP@transfer.astellas.us  Could not load program /usr//bin/ssh:   Dependent module
                                                   /usr/sap/BDR/sapboe/sap_bobj/enterprise_xi40/aix_rs6000_64/libz.a(libz.so.1) could not be loaded.   Member libz.so.1 is not
                                                   found in archive   Connection closed   send: spawn id exp7 not open     while executing "send "Astellas123\r""