Hi alireza,
As per your details, you have an HD files which you want on a dvd. And, you have first exported this file to Quick Time output. Now, if you want it on a dvd, you can use your HD source file itself. Import it into Premiere, drag it to timeline, select “File>Export>Adobe Media Encoder”. When the AME UI comes up, select MPEG2DVD as format and select the settings which you want to use to export.
The DVD supports only SD sizes, so you will have to scale down the frame size of your video.
Also, the duration of your source file is important because the DVD has got its limitation storage-wise. you should take a look at estimated file size before you export.
now, you can import the AME output into Encore and burn it onto a DVD.
If you still face any problem, do let me know.
thanks,
Prateek