help my subttitles are unsync in encore dvd2.0

I create a file .txt in the subttitle workshop save in encoredvd 2.0 format
(utf-8). I use the AVI in 29,97 fps, and the subttitle in the same fps.
when I import to encore dvd the subttitle sync in the begin but it out of sync
at each frame, as it has 29,971 fps. but the .txt file are normal.
exemple:

00:02:37:20 00:02:47:19 e você se foi, "me deixando"
em pedaços
00:02:48:26 00:02:52:23 que saudade amor...

in timecode encore dvd the last subttitle has been like this:

00:02:49:00 00:02:52:27 que saudade amor...