SARSimulation Terrain Correction, failure in Co-registration or Terrain Correction step

Hello. I’m using the SAR Simulation Terrain Correction Operator on a S1A GRD image. When I do the SAR Simulation it works fine (Simulatd Intensity and Sigma similar to original one). But when I try the SAR Simulation Terrain Correction there is a good computing of the local incidence angle but no output (black image) for the sigma corrected band.
I am using a local DEM in tiff.

Any suggestions?

It needs to be able to coregister the simulated image to the input image. How different do the two look? You may want to try using different windows sizes for the coregisration.

Thanks, they look quite similar, I’ve tried different window sizes for the coregistration, and I’ve added GCP (13 points) manually.
When I do the Coregistration only it works well, I’ve got the stack with master and slave images.
But when I try to carry out the “SAR-Simulation Terrain Correction” which includes the SAR Simulation + Coregistration + Terrain correction, then the coregistration does not work well (the warp part), I’ve got the message “Sigma_VH does not have enough valid GCPs for the warp”

Here is a working example to coregister Sentinel-1 SLCs with an external DEM and which outputs both, measured and simulated Intensity.