custom disc space, not filling up all available space

Hi Guys

I have a 14Gb MPEG-2 project exported from Premiere, I wish to make a DVD now with chapters etc.

Now, when in die Build tab, i want the disc size to be set to custom 14Gb so that I get my full quality and file

from the original video that I exported from Premiere.

With this said, it only fills up 6.8 worth of space, regardless if I chose a dual layer 8.5 size or custom size.

Please refere to attached picture.

Please advise

Regards

Louis