Internet Explorer 11 won't set cookies on a site

For some reason IE11 (only IE11, tested with other IE9 and IE10) won't create a session on a site i've been working on. So this means that a basic functionality such as site login won't work.

On other browsers this is working perfectly. The site URL is http://www.tc.mk (also http://www.tc.com.mk)

I researched a bit and found out that IE won't work with domains with underscore.. but my domain doesn't have one so what could be the problem?

Thanks!

PS: Not sure if this is the place to be asking this so sorry if i made a mistake.