Problem with GB (save as PNG)

Hi, i’m new on Esa Snap.
I have created a Graph Builder to process all together using Batch Processing a set of data downloaded from Copernicus Open Hub.

At the end of the process I have two output, one in VH and one in VV.
I would save each of them in a .png file.
Using the ‘Write’ tab, it creates an empty png file.

These are some screenshots.