Problem:Region Render

[radiosity1980]

Hi to all, I have had some problem whit the render-region.
When the render is finished, if I do a region, the old frame is deleted.
(I don’t change any parameter between full and region-render
I have noticed that it’s happening when I use much render elements.
Can you help me?
sorry for my poor language

[tashko.zashev]

Hi,

Which V-Ray version is that?
If you have added a render element just before the region rendering then the VFB has been cleared.
Can you post simplified version of the scene to test here ?

[Dave_Wortley]

Render Settings → Settings Tab → System Rollout → ‘Expert Mode’ → Previous Render - set to “Unchanged”

Turn off show Calc phase for Irradiance map or light cache.

[radiosity1980]

I have tried your solution, but unfortunately they have not solved the problem.
I finally found the problem.
The problem was caused by “AutoMultiMatte” script (see the image).
thank you all for the help
sorry for my poor language