SAR Simulation problem

When I was use Sentinel1 data with SAR Simulation in SANP,at first,I do split with s-1 TOPS Split tool,and then I do deburst with s-1 TOPS Deburst tool. Then I do SAR Simulation,SNAP error:
A problem occurred during the target product initialisation.
Message:incidence_angle tie point grid not found in product.

What’s problem with me??Help!!

did you stick to the BEAM DIMAP format during the processing?

I just tested it with a SLC product, I applied Split, calibration (not mandatory) and Deburst, then SAR Simulation, and it worked.

I had to use GETASSE because the test data was not covered by SRTM

Thank you so much!
I save as geotiff-bigtiff format during the processing.I will try the BEAM DIMAP format.

What is GETASSE?Is it a kind of DEM data?Thank you!

GETASSE is one of the automatically downloaded DEMs which are supported by SNAP. If your area lies between 60° North and 60° South, I recommend to use SRTM 1Sec HGT (AutoDownload) whenever you can.

Has it worked to save all processing steps as BEAM DIMAP? It conserves the metadata required by some radar tools better than general formats. In the end you can still export to GeoTiff, please check the notes on this in this tutorial: Export of products from SNAP