Height value in div in percentaje not in pixels

This is my div

but i need the heigth value with percentage, but if I change to 100% or any value with percentage has the minimal size and I cant see anything even the colums title. Any help please. Thanks!

I had the exact same thing happen to me. The FAQ actually helped me out.

docs.dhtmlx.com/gantt/faq.html

Thanks a lot!