Akismet-WP-Contact Form localisation problem

I started using Akismet-WP-Contact Form Plugin for my blog in Tamil language here. I use Poedit to translate and save as .mo file. I made wpcf-ta.mo from the pot file provided along with the plugin. I find a peculiar phenomenon. While some of the localised strings work, some others don’t. But Bingo, after a few days some more strings start working! Why does this happen? I flushed the browser cache each time I make the change, upload and refresh. But same thing happens. Still there are some messages which refuse to show translated strings as can be seen here.

Could someone please help me.

Thanks in advance.

Regards

S.K