Logstash missing few lines /not detecting new files

I am using Logstash 1.5.2 and elasticsearch 1.6.0 in windows 7

Below issues are could not address myself.

1. When i am using file input with wildcard option the newly added files are not getting processed.
2. If i made any update on new file then it will get process but some lines are ignored.

consider file1 having 5 lines of log its getting forwared into logstash.
if i am creating file2 (new file) with 10 lines its not getting processed. it will get processed after i made any update on new file but first 5 lines are getting ignored.

if i set start-position => "beginning" its re-scanning all the files when ever my service/system restarted.

any help would be greatly appreciated.