Premiere CS4 and pillarboxing 1920x1080 AVCHD to 16:9 DVD NTSC

[tat2jr1]

I'm new to Premiere CS4. I'm using Canon HF11 30p MTS files, so I'm using the 1080i30 (60i) settings. Import my AVCHD files. When I try to use Adobe Media Encoder CS4 to downsample the 1920x1080 AVCHD to 16:9 DVD NTSC I get pillarboxing on the sides of the DVD file. I don't in any of my other video editing programs. Why do I ONLY in Premiere, and how can I fix it?