Class 'Crypt_RC4' not found

1) sftp connect in php

2) nfstp connect in php 

Error Details: 500 - Class 'Crypt_RC4' not found in /data/vishal/public_html/phpseclib/Net/SSH2.php on line 2193. Error Type: 1

solution:- 

put this below line top of the code

1)         set_include_path(get_include_path() . PATH_SEPARATOR . 'phpseclib');