Gpt Terrain-Correction error

Hi,
I am trying to process S1 data using gpt. I used gpt for the calibration, multilook and speckle filtering. However when I use it for terrain correction I receive error message. the used command and the error message are as follow:

./gpt.sh Terrain-Correction -Ssource=/data/omar/tif/speckle.dim -t ‘/data/omar/tif/terrain’ -PdemName=GETASSE30 -PpixelSpacingInMeter=10.0
Terrain-Correction: Determinant is 0
org.esa.beam.framework.gpf.OperatorException: Terrain-Correction: Determinant is 0
at org.esa.snap.gpf.OperatorUtils.catchOperatorException(OperatorUtils.java:397)
at org.esa.nest.gpf.geometric.RangeDopplerGeocodingOp.initialize(RangeDopplerGeocodingOp.java:305)
at org.esa.beam.framework.gpf.internal.OperatorContext.initializeOperator(OperatorContext.java:483)
at org.esa.beam.framework.gpf.internal.OperatorContext.getTargetProduct(OperatorContext.java:264)
at org.esa.beam.framework.gpf.Operator.getTargetProduct(Operator.java:323)
at org.esa.beam.framework.gpf.main.CommandLineTool.runOperator(CommandLineTool.java:282)
at org.esa.beam.framework.gpf.main.CommandLineTool.runGraphOrOperator(CommandLineTool.java:260)
at org.esa.beam.framework.gpf.main.CommandLineTool.run(CommandLineTool.java:170)
at org.esa.beam.framework.gpf.main.CommandLineTool.run(CommandLineTool.java:121)
at org.esa.beam.framework.gpf.main.GPT.run(GPT.java:57)
at org.esa.beam.framework.gpf.main.GPT.main(GPT.java:36)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at com.bc.ceres.launcher.Launcher.launch(Launcher.java:154)
at com.bc.ceres.launcher.Launcher.main(Launcher.java:56)

Error: Terrain-Correction: Determinant is 0

Could you provide the input product name and the processing applied to it before the terrain correction?
Thanks

GETASSE30 is global but the quality of it is not very good (it has a lot of artifacts).

well, the original product name is “S1A_IW_GRDH_1SDV_20150311T061136_20150311T061201_004980_0063C4_A3F4.zip” which was processed by running the calibration, multilook and speckle filter. The later output is named as speckle.dim as shown by the provided command. The commands previously applied are given below

./gpt.sh Calibration -Ssource=/data/omar/raw/S1A_IW_GRDH_1SDV_20150311T061136_20150311T061201_004980_0063C4_A3F4.zip -t ‘/data/omar/tif/cal’
./gpt.sh Multilook -Ssource=/data/omar/tif/cal.dim -t ‘/data/omar/tif/multi’
./gpt.sh Speckle-Filter -Ssource=/data/omar/tif/multi.dim -t ‘/data/omar/tif/speckle’ -Pfilter=Median -PfilterSizeX=7 -PfilterSizeY=7

when I used the default option of dem I face the same error message
./gpt.sh Terrain-Correction -Ssource=/data/omar/tif/speckle.dim -t ‘/data/omar/tif/terrain’ -PpixelSpacingInMeter=10.0