Hi,
Thanks for the file, I've got it and found the problem with it.
Now, the issue here is that this file is seriously wrong, I am not sure on how Excel opens it at all, but in one part of the fie it declares to have 3 sheets ("sheet1, sheet2 and sheet3") and in another it provides a single "table1" sheet. This is confusing FlexCel, who doesn't know what to do with the "table1" sheet, as it was expecting sheet1, sheet2, and sheet3.
FlexCel just discards table1 (And this is why you end up with a file with 0 sheets, which is invalid), Excel seems to read it anyway and add it to the sheets.
Now, I don't really know what to do with this. The file is without doubts wrong, so not reading it fine is expected, and the real solution would be for you to speak to whoever is creating those files and tell them to fix them.
On the other hand I understand that this "real" solution isn't always possible, and that's why we try always that we can to add some support to read those files anyway even if they are wrong. (there is already a good bunch of FlexCel code dedicated to dealing with buggy third party files). But in this case ignoring the error and loading the file anyway can be kind of dangerous, not for this file of course (which would load fine), but for other files which might contain in the future, say Excel 2015, new kind of sheet types that FlexCel can't understand, and the right thing to do with those sheets is to ignore them (as we currently do), not just to try to load them as normal sheets.
But well, I'll investigate if there is some way we can workaround this without compromising the correct loading of actually unknown sheet types, and without affecting performance for actual valid files. I'll get back to you tomorrow with more information.
As a final note, I'd like to repeat that normally "excel can open it" isn't a good way to find out if a file is valid, The test should be "If I open this file in Excel and save it, then FlexCel can't still open it". In this second case, it would be a problem in our side. In the first case, it is most likely a problem in the file.