Using tamil in writer

Libre office
Version: 4.2.7.2
Build ID: 420m0(Build:2)

I have installed the keyboard and font as noted from askubuntu. Tamil keyboard is also displayed. But unable to type in Tamil.

Would appreciate help.

Thanks.

I do not have any expertise in tamil but here is some advice from just reading to LibO options.
Have you set the tamil option in LibreO? In Linux that would be TOOLS > OPTIONS > LANGUAGE SETTINGS > LANGUAGE > COMPLEX TEXT LAYOUT (CTL) > TAMIL. These settings are required to use tamil.
I believe there is also the translated user interface and help for Tamil. LibO 4.2.7.2 is quite old know. Have you thought of updating to a later version in case that helps your Tamil requirement.
Hope this helps Peter