"Steady state error"

I got an Error Message as follows: :o

ERROR: Unexpected exception occurred. Please see log file for details. Exception message: Steady state error in iteration 1
Exception: Steady state error in iteration 1: Q cannot be determined on reach kanlidere,0,11454.23046875

Anyone has an idea to solve it?

For example, When I remove Hydraulic structures (culverts and weirs), it works  but Why???
OR, I changed HD: from Steady State to Parameter File (without adding any files just change!) in Simulation Tab in Initial Conditions, and it works again! but Why??  :-\

Kind regards,

Hasan