Your file is not of the correct format. Note that the format documented on this page is for importing a cross-section geometry into RiverCAD. Note that DAMBRK generates a ***.FPM file that you can then import into RiverCAD's Floodplain Mapping Module. These two files are different formats.
I have enclosed a sample FPM file below.
29500 7.00
30000 8.08
30500 9.42
31000 10.58
31500 11.53
32000 12.93
32500 13.73
Note that the first column represents the cross-section number, and the second column represents the water surface elevation.
Please feel free to contact me directly if you have any questions or need any further information.
Sincerely,
Chris E. Maeder, M.S.
Senior Technical Engineer
chris.maeder@bossintl.com