Platform behavior jittery when angle constantly changing

Hi, is there any way of preventing jittery movement of a sprite with platform behavior when the angle of the platform on which the sprite sits is constantly changing? E.g. a swinging platform. At the moment the sprite shakily moves right or left instead of moving smoothly as the platform swings.

The capx link below illustrates the issue using a platform pinned to a pivot with sine behavior and angle movement.

Can't post links so add https before the link below:

sendspace.com/file/dmn1gm

Are you using raw dt?

Just using platform behavior for the sprite and sine behavior for the platform, so I think the answer is yes. Example capx in my first post.

yea, the 'dt' value jitters because the frame rate is not constant.