Java EE (Java Enterprise Edition) General Discussion

I'm using GZIPInputStream in order to read data from zipped file.
It worked perfectly from command line. I have to execute the same code from crontab and it gave me the exception:
java.io.IOException: Not in GZIP format
It tries to check the GZIP_MAGIC number and for some reason failed.
The stack trace I'm getting points to GZIPInputStream constructor.
GZIPInputStream input = new GZIPInputStream( new FileInputStream( fileName));

Any help will be highly appreciated.
Thanks,
Arnold