Dear Jack :
Note that the split flow routine in HEC-2 is not that robust. I have seen similar problems with the split flow routine.
I would recommend running each profile separately. You can easily do that. Select Reach | Profile Description. The RMS / RiverCAD software will then display the Profile Description dialog box. Select to analyze a single profile by "tagging" it. The run your analysis. Unfortunately, you will need to copy each analysis output file to a separate file name so that you can later retrieve the results.
If you have any additional questions or need any further information, please contact me again.
Sincerely,
Chris E. Maeder, M.S.
Senior Technical Engineer
chris.maeder@bossintl.com