So many time you enabled gZip or Deflate but still compression not working.Sometime issue is with hosting provider(e.g. 1and1, Hostgator, GoDaddy etc.) which does not enable deflate on shared hosting.
Solution To Enable Compression
Add these two lines in php.ini file
zlib.output_compression =1 zlib.output_compression_level =9
If some of your files are compressed and some are not, then your gzip is working but you might have missed definition in gzip_types
Resources for WordPress blog to output pages compressed in gzip