Hi All,
Regarding error no. 25, I have sorted it out; so no worries.
A good lesson is water level can build-up for many different reason, not only for instability; I did not want to sort it out by a short-cut, and so I did not modify the default value (4) for the WL_EXCEDENCE=4 in the MIKE11.ini file.
Because I have a tabulated structure just d/s of the sluice, that structure was the cause of water level build-up; in previous all runs, the sluice was operational by certain rules, and now the sluice is 'Always Open'; as a result lot of water started entering the channel, and exceeded the Q-H range in the tabulated structure, and as a result, discharge became zero above that water level, whereas lot of water was entering that channel from another channel. So, I extended the Q-H range in the tabulated structure, and everything is fine.
Thanks for your reading of my previous post, and hope my experience becomes useful for potential users of MIKE11.
Regards