OpenGeoSys Tutorial II Ashi

Hello everyone.
I’m trying to simulate watershed water flow with OGS-5, and when I follow Tutorial II to simulate the Ashi River(Chapter 3), the last output vtk file shows an abnormal value in paraview, and the OGS has the following warning:
Warning: no boundary conditions specified for GROUNDWATER_FLOW
Warning in CRFProcess::ExecuteLinearSolver() - Maximum iteration number reached
Can someone help me ?Thank you.


This is the process

I found that when I used the Ash River boundary condition, which with the constant 137 in the tutorial, it was always wrong. But when I used the Ashi River boundary condition with river slope in Chapter 5, it worked. Does anyone know why? Thank you very much for your answer and help.