HDV sourced footage looks great edited in FCP, turns to crap when going to DVD Studio Pro

Hi All,

I am working as an editor for a small production company and am quite new to the game.
At the moment we need HDV 1080i (sony fx1e) projects edited onto FCP and put onto DVD. Sadly whilst looking amazing on FCP, the projects on DVD look shocking! My job is on the line and would really appreciate some help.

I am editing on FCP (latest version) Sequence preset HDV - 1080i50, Capture preset HDV, DCP - HDV firewire. Then exporting to compressor and using DVD best quality for 90 mins. Then onto DVD studio Pro to burn but the quality seems to have completely gone when finally put onto DVD. (DVD studio pro preferences - general - resolution 1280 x 720p display mode, 16:9 letterbox. Project - dvd standard-SD DVD, video standard PAL (from the UK) encoding field order - auto, mode - two pass VBR, bit rate = 21.0 mbps, max bit rate = 27.0 mbps, motion estimation = best. - method background encoding.

If someone can help me it would be most appreciated! Thanks for reading.

Alex