Hi, all. 

I have UltraDataSource and bound UltraGrid. At the runtime i change UltraDataSource structure and same time i get the next message from the grid:
---------------------------

Data Error

---------------------------

Unable to retrieve list object for the row. This typically occurs when the UltraGrid's row collection gets out

of sync with the underlying data list. This can be the result of the underlying data list failing to raise

proper notifications to notify the bound controls (UltraGrid) of change in the data list, particularly of adding/removing rows.

UltraGrid will resynchronize the row collection with the data list, adding/removing grid rows as necessary and continue

to operate normally. However this resynchronization process can be inefficient if there are lot of rows. If you are using

a custom IList as the data source and you are experiencing performance issues in association with this error message, you

may want to make sure that the data list raises proper notifications for changes in the data list. To raise notifications,

you will have to implement IBindingList interface on the data list and raise IBindingList's ListChanged notification.

---------------------------

OK  

---------------------------

Why may this occured?

Thanks in advance.