Make sure that all the necessary data are entered. Hydro, Bed Material Sediment, Sediment Properties (transport equation), Sed Sources (at least 1 must be entered for the model to run, can make this value very small if you do not think many additional sediment sources exist beyond upstream bed material). Also, make sure that the cross sections within each sediment reach are contiguous with the next, meaning that adjacent sediment reaches start at a the next downstream-most cross section from where the upstream sediment reach left off.