Camel not able to pick 0 byte file -

i have camel configured pick file ftp. empty file placed fail pick , log same event continuously:

2015-07-14 19:53:11,005 warn  [org.apache.camel.component.file.remote.strategy.ftpchangedexclusivereadlockstrategy] (camel (camel-1) thread #0 - ftp://abc.com/responsefiles) cannot acquire read lock within 20000 millis. skip file: remotefile[refund07102015.141730.csv] 

my camel config :

sftp://[servername]/responsefiles?username=[username]&password=[password]&readlock=changed&readlockcheckinterval=5000&noop=false&premove=.processing&move=.done 

you need configure readlockminlength=0 allow picking empty files. see more details @ http://camel.apache.org/file2