MB with Splines

[houou]

If splines are constant I can get MB
But when the splines change in quantity I cannot.

I thought TyVertexVelocity was meant to fix this creating some kind of aproximation?
Strangely enough it shows the right velocity vectors in the modifier but Vray just wont take it.

is this a Vray or a Tyflow issue? or it is expected?

Thankyou!

[tyFlow]

I'm not able to check the file at the moment...is your VR moblur interval center set to 0, so that the center of the moblur interval is a whole frame? Please check the tyVertexVelocity modifier documentation for more info.