Dear Fredrik :
Note that you must define the cross section geometry with the same number of top widths at each cross section or DAMBRK will report this as an error. So, if you start with 5 top widths, then you need to maintain that number of top widths throughout the modeling process.
Also, you might have left some top width entries blank for storage or floodplain data at some of the cross sections where this data was defined completely at other cross sections. You can enter a value of 0.0 to get the warning message to disappear.
Sincerely,
Chris E. Maeder, M.S., P.E.
Senior Technical Engineer
chris.maeder@bossintl.com