GEOPAK Drainage error message

I am getting the following error message on a certain drainage project:

"Time of Concentration Outside Rainfall Table"

I have checked all of my drainage areas and all have a manually entered Tc of anywhere between 4.9 and 15.2 minutes, well within my library's rainfall data.  My minimum Tc is set at 5 minutes.  The one area that I have a Tc of 4.9 processes using the minimum of 5 minutes, which is what I expect.  All of the others seem to produce normal results with their larger Tc's.

Should I be concerned about this error message?

Josh Mauritz

MS v08.11.05.17

GPK v08.11.05.39