Data save error in MVC after input auto-number column

I’m working with dhtmlxGrid on ASP.NET MVC.
Data saving function did well but now it doesn’t. I think that’s because of added numbering column.
I used ‘cntr’ in setColTypes to make auto-numbering feature.
But when I modify data in grid, it throws error and data turns red color in grid. (maybe shows error?)
Here is my project that you can download. Please help to figure out what is problem…

Unfortunately the problem cannot be reproduced locally.
Could you please, upload your sample once again.