Which tutorial?
The DEM-WrpEdit Tutorial?
If so then it assumes you have a properly prepared DEM first.
Possibly you are using the whole DEM, resampled to 50m.
You actually need to cut an area 12.8 km X 12.8 km from the resampled DEM, for use in WrpEdit.
In the absence of a tutorial showing you how to do this, if you send it to me, I will cut the required area for you.
Please send a picture of the DEM also, clearly marked with the approximate area on your DEM that you require.
mcnicoll7@yahoo.com
Planck