Mac Book air Display problem

Hi,

I have a LG 22MP47d-p monitor.

http://www.lg.com/hk_en/monitors/lg-22MP47D-P/technical-specifications

I was using it connecting from thunderbolt to VGA cable without any problem with my

Macbook air 11″ (mid 2012)

OSX El Capitan

on 1920×1080 resolution without any problem.

Now I bought a new Macbook.

Macbook air 13″ (early 2015). With the same configuration I can not see any resolution higher than 1280×1024.

I will be appreciated for any kind of help here.

Thanks,

Deniz