I/I subroutine

We have been trying to use the I/I option with SWMM4.4 that uses the F3 and F4 cards and the H5 card. It just does not seem to be working out as we always get a message of error stating the the time step in the F3 card (TSTEP) is not the same as THISTO (even if it is indeed the same). THISTO is 5 minutes and we input the same in the F3 card. If somebody at CDM is listening to this or Dr. Huber, we would like to hear from you and get a little bit more of information that what is in the documentation. We tried to read between the lines and tried many different things but we did not succeed after a full day to even get the thing working. An example showing a file that does indeed work with the E1 card and the F3, F4 and H5 would be useful. We badly need some help on this as we are running out of time (and money...)

Also, it is not clear how the H5 cards are used. Do we have one for each subcatchments where we want to have the moderately fast or slow response hydrographs to be calculated ? If so, how is the model told where to input the computed hydrograph if the NGTO is not specified in the H5 card ? Is there a limit on the number of H5 cards ?

Thank you for any help that would come for this topic.

That error message could be triggered by using 0.083 decimal hours on the E3 card for 5 minutes (if you did that).I Had that happen today; switched to integer minutes on E3 and the problem went away. I was not using the I/I logic, so this may not help you. Good luck, Ron K.