I designed an application using GroupBy method as an option to the user. This allowed the user to display the same data by different, groups. All of a sudden I saw today lot of blank rows on the top of the gird when I used Groupby method.

Is it because I changed the defintion of Grid or the data has some problems? Have you come across this situation. Now I removed the GroupBy option from my application. Any help is appreciated.

It hard to say , without ability to reconstruct issue, but the possible reasons are

- non unique IDs ( they will cause unpredictable results during grouping )
- usage of grouping with such modes as paging and smart rendering ( modes are mutual exclusive )
- there are known issues with some third party libraries ( prototype for example ) which extend base js object and may corrupt grouping if cell value will be equal to the name of methods ( contact us if you need fix for that issue )

If it possible - please provide any kind of sample or demo link, where issue can be reconstructed.