ERROR: Processed flow areas must be positive.

Dear all,
I am simulating a river model with some cross sections. Unfortunately, I faced this error:

ERROR: Processed flow areas must be positive.
                    Cross section at reach 'XXXX', chainage 2000.00 m.

Please help me to remove this error.

Cheers,
Mahsa

Dear all,
I have identified that my the error appeared due to a problem in my cross sections' datum. I am working on it.
I just want to guide users who faced this error.

Cheers,
Mahsa