[MacDV] iMovie 3.0.3/exporting problems

[rdc]

Hello, this is the first time I've used this listserve, so I hope I'm 
not asking a question that's been discussed many times.

I have iMovie 3.0.3 and am having trouble exporting to a VHS tape.  I'm 
using a Sony converter box & never had trouble when I used iMovie 2.0.

When I click on File-Export to Camera, then click export, the next 
screen pops up and it always says, "Make sure your camera is in VTR mode 
with a writeable tape in it."  I have a new tape in it so the tape 
shouldn't be a problem.

Under preferences I have
General: Play sound when exported completed
use short time codes
New projects are NTSC
Imports: Clips pane; automatically start new clip at scene break
Advanced:
extract audio in past over
filter audio from camera
play video through to camera

Is there some little thing that I'm forgetting?  Some button I haven't 
clicked?

Thanks for the help.