tween with meshinstance

Hi all,

i've a spatial with a meshinstance.

I'm trying to tween interpolate the z translation without success:

func _on_Timer_timeout():
 	mytween2.interpolate_property($MeshInstance,"translation",translation.z,translation.z-1,1,1,0)
	mytween2.start()

This code is in a timer that get executed. If I executed the following code it work, but without tween

if $MeshInstance.translation.z < - 5:
	$MeshInstance.translation.z=-1
$MeshInstance.translation.z=$MeshInstance.translation.z-1

What i'm doing wrong? I would like to have the tween working. I got no error as well.

Thanks

ok, i've to use a vector 3. All clear.

I haven't used tweens yet, but thanks for following up with the solution.