thank you Dan . Expressio work fine , parameter changes , but ! strangely enough, it works in the beginning of the clip but does not work at the end of clip . I even tried to do at the end of – 2 frames
else
linear(time,outPoint-thisComp.frameDuration*2,outPoint-thisComp.frameDuration,180,0)
but to no avail
on keyframes , it work fine . maybe it’s a bug AE